A major cleanup, disentangling net_if and ssl_if.
Pulled a lot of common logic into the core and reduced size of net_if implementations.

CL: Mongoose net_if and ssl_if refactoring

PUBLISHED_FROM=29bd4dcb264a1fd96b3dd164e2d880e1c2c0921e

Consume buffer as soon as we know there is no boundary there, no need to delay until next chunk arrives.
This prevents stall where buffer fills up in one go and next chunk never arrives.

CL: Fix an edge case in multipart HTTP upload parsing

PUBLISHED_FROM=025f9001d272df2a75ece22b199b1944d5db9840

In preparation for making moving to lib.
Reduce amount of makefile copypasta a bit.

CL: none

PUBLISHED_FROM=70a016491f9605e37708385bdd698f48a8d64119

 * Limit total amount of headroom, in absolute terms (`MBUF_SIZE_MAX_HEADROOM`).
 * If unable to allocate with headroom, fall back to allocating the required minimum.
 * For mOS, set default `MBUF_SIZE_MULTIPLIER` to 2 to avoid floating point operations.
   Since max headroom size is now capped to 128 bytes, this will not result in much of a bloat.

PUBLISHED_FROM=11d4fc65a46a805bb7c8960f89a3d0b753c58bb8

mongoose: fix formatting

mongoose: fix formatting

mongoose: remove debugging messages

PUBLISHED_FROM=1194e018001cc5f2b598096593d7aac4ec8dc04d

PUBLISHED_FROM=00e8634913232eb2e50a0d739f85e81706dbc400

PUBLISHED_FROM=63ce52177f5f13cb76f0fcb4689efb65a04318a2

freshen: implement ota rollback

freshen: api for rpc

freshen: implement rpc api (without transport)

PUBLISHED_FROM=9f935f676161c81464a0dc53d5d8d085b2437ffb

PUBLISHED_FROM=9a81cc34aa0039a75c851bc3685055f46936252e

CL: Fix mg_socketpair for lwip + UDP

PUBLISHED_FROM=6dd09136b3837016026523fb34acb5cc893cadbe

Fixes https://github.com/cesanta/mongoose-os/issues/394

CL: Fix buffer size passed to inet_ntop()

PUBLISHED_FROM=4a6702527627ccbb780f45200274b09a28be69ee

E.g. if `ASSERT_EQ(myfunc(), 123)` fails, `myfunc()` would be invoked again to print the actual value.
This can cause confusion sometimes.
To avoid this, we cast arguments to double, which is wide enough for most cases and we provide a variant for 64 bit value types for when it's not.
We also perform a check and fail if argument to the check results in loss of precision.

CL: none

PUBLISHED_FROM=a14551289d92e8a5dead21d16471ebddebe938a8

CL: none

PUBLISHED_FROM=ab7f50e1c68154832e862ebfb4a02d385ef7c6be

PUBLISHED_FROM=92604e1b7c65009a6214fea9f1b2460df721d38e

Which is a replacement of (deprecated) `mg_http_parse_header`, but,
similarly to `asprintf`, allocates a new buffer if the client-provided
one is not large enough.

Also use it throughout mongoose code, and thus some header-related
limitations are removed; in particular,
https://github.com/cesanta/mongoose/issues/813 is fixed.

CL: Mongoose Web Server: Deprecate `mg_http_parse_header()` and implement `mg_http_parse_header2()` instead, which allocates a new buffer if the client-provided one is not large enough (similarly to `asprintf`).
CL: Mongoose Web Server: Fix limitations of header value lengths, e.g. when parsing authentication headers such as nonce, etc.

PUBLISHED_FROM=c75b1bbbbdb294ea85075ce69b1368f115fdd1ef

PUBLISHED_FROM=d52aea1648ed8ec8dd2e71168884795d995b1826

CL: none

PUBLISHED_FROM=ee76407d89f3fcbe3da23810117a374d06af0a25

To properly fail a test in a subroutine, return value needs to be passed up.
This snippet makes it short.

PUBLISHED_FROM=2f6328b5eb2921a4caa53d8887c02f73a5d817ea

PUBLISHED_FROM=3cd6dd7f04b650ca637788d1017b6b5146c79569

CL: Mongoose Web Server: Add UDP client example

Resolves https://github.com/cesanta/mongoose/issues/886

PUBLISHED_FROM=fcce2f1de3a800147e9246ffa01c428c1b8f552b

In certain files it was necessary to make tests work from public
mongoose repo, so this commit makes things consistent.

PUBLISHED_FROM=694454d0ff007229c65d524a2a2beaf126420f15

PUBLISHED_FROM=78acb18d597b6f47f31da13087fa6685f21ce445

PUBLISHED_FROM=331821dcd1f7dc8a94581cd8a9b51aa00a89fddc

Even though it makes no prectical difference due to the way amalgamation works

CL: none

PUBLISHED_FROM=6977833f2b469e5b969385ad9ae21a28af76746f

CL: none

PUBLISHED_FROM=d6ebe5fa88c61ae3b8569897d9b09d54610bec73

CL: Mongoose Web Server: Remove tunneling functionality which was used by nobody

PUBLISHED_FROM=38b9e8ae7b0a5a1dbba5cff4074843dc681267d3

CL: Mongoose Web Server: Publish sources and tests

Resolves https://github.com/cesanta/mongoose/issues/745

PUBLISHED_FROM=7ecd7a3c518cfa614a6ba0838678dcb91b75a8c0

Before it resulted in an endless recursion.

Resolves https://github.com/cesanta/mongoose/issues/871

CL: Mongoose Web Server: Fail if passed a NULL handler to `mg_bind` or `mg_bind_opt`.

PUBLISHED_FROM=376e5d330a643fa530f6a27a422a1500f986c721

CL: Mongoose Web Server: Digest authentication: Fix nonce validity check (expired nonce or nonce from the future did not cause the the check to fail)
CL: Mongoose Web Server: Digest authentication: Fix nonce request value; it worked before because nonce validity check was broken as well
CL: Mongoose Web Server: Digest authentication: Add `nonce` argument to `mg_http_create_digest_auth_header()`: clients should use the value received from the server's authentication request.

Resolves https://github.com/cesanta/mongoose/issues/809

PUBLISHED_FROM=5e59f90ed6b2a4311ed6763159da81c2aaf6af4c

CL: Mongoose Web Server: Websocket: Respond to Ping with Pong
CL: Mongoose Web Server: Websocket: Properly close a connection with Close frame (in response to a client's close and when protocol failure is detected)
CL: Mongoose Web Server: Websocket: Fix support of fragmented messages
CL: Mongoose Web Server: Websocket: Add support for control frames interjected in the middle of a fragmented message

PUBLISHED_FROM=e2b3794aaacc64633540c493194cccc62afa2077

`path_info` was dereferenced without checking for NULL, and a few lines
below, it was checked for NULL.

CL: none

PUBLISHED_FROM=9f14dc68c152b9b1119b276f047686d831bace38

CL: none

PUBLISHED_FROM=f165b556582f712c2c1c752e01c41d22fe593397

PUBLISHED_FROM=f3c1fcf015f6f72eca2eb3d5dad469cd66a837a9

PUBLISHED_FROM=7660e252e1ac84bf2245718c548fb00288ff4e47

PUBLISHED_FROM=413f5073b0fc267d66ce04d8d40e9e9d7abac94d

CL: none

PUBLISHED_FROM=9d68cdc298c520798468b43a19c84251bd0c21b4

Integrates https://github.com/cesanta/mongoose/pull/884
Closes https://github.com/cesanta/mongoose/issues/883

CL: Mongoose Web Server: Don't use user_data in mqtt server

PUBLISHED_FROM=7785784a766e0ba7514bbba604cde14e7bad3f73

CL: Mongoose Web Server: Fix mg_parse_multipart in case of malformed request

PUBLISHED_FROM=9b33b03e9ab2ca204ad2f8d061df169246644072

CL: none

PUBLISHED_FROM=9c13882517374644c6d799976f1048f04ae446d7

CL: Mongoose Web Server: Fix publish-subscribe example

PUBLISHED_FROM=04fdb66c1d4eb56798a5be2634f9f9bb2f18f288