Fixed bug in websocket handshake:
now adding Sec-WebSocket-Protocol header in handshake response.

PUBLISHED_FROM=e4a71ff9dc4aeec63db40cb7f356dc5b25c1215a

PUBLISHED_FROM=f97569ae2f31ab94ce4875eae4d0a198f719c388

https://forum.mongoose-os.com/discussion/comment/4620/#Comment_4620

PUBLISHED_FROM=679dd48e078615ef4f57d1879957b734f549ef2e

Ignore all the mess, this is just the beginning...

PUBLISHED_FROM=41ab3c5af0b1d07204619dd4d8dc2e84b6a54f32

PUBLISHED_FROM=73d6767e4aaa7249eeb5d76f9e7160be041292ca

PUBLISHED_FROM=62c73e5fb4f70e2b5b8824ce092012508640b173

PUBLISHED_FROM=7b9c85e7708721f2c6d0e2fc8ad5c32c61b48854

Fix headers that didn't have it

PUBLISHED_FROM=ce8140783d4b661f16278a4a5adc957b21965473

PUBLISHED_FROM=33957356e1510b73b37768496c74a6bf12630215

Change the API to heap-allocate the string and get rid of a bunch of fat stack buffers.

PUBLISHED_FROM=c793dc64a9a044a9769d92ea16859f5d704a2181

PUBLISHED_FROM=2fc7b59b2edd0f473acd22067439471778acef8e

PUBLISHED_FROM=ed2c39b9e00a7374af7fed5af0c9acd6c330334a

PUBLISHED_FROM=6e56c250fe62010e25b6ed489c0d608163ba629c

PUBLISHED_FROM=c6c31d47eedcfe09b675e3f56d967da5b22809f6

PUBLISHED_FROM=a0dd26c00b41363f1cc58c28f530fbdf272ed146

Also allow disabling conmpression and forcing server cipher list.

PUBLISHED_FROM=5539deec9c2382ba34597872dd7f3a5abc0cc311

PUBLISHED_FROM=4306e870e2cab854febb6becc198ca2247e2e002

PUBLISHED_FROM=4d4d49136e13ba8035d452a4f64fcaf48f15bdb3

PUBLISHED_FROM=f2821b104f8f2fc196ce4064b7c9f35ea152368d

Write unit tests for some mg_str functions.

PUBLISHED_FROM=1fc7e1d5d5ef259d4023f295aec8651caa3e7e86

h/t @hendrikw01

Fixes https://github.com/cesanta/mongoose/issues/826
Closes https://github.com/cesanta/mongoose/pull/831

PUBLISHED_FROM=d5e1285bee9bcbb85d581ee62972a2fde7d9c0db

PUBLISHED_FROM=1803e726eee7bb64496d70389655083eb70257ab

PUBLISHED_FROM=efa9cc3aaf0c5ae8841e029370f882b615cebf1b

PUBLISHED_FROM=b8f538f87e034452032284d45b78090338e87f72

PUBLISHED_FROM=16ae777c949caf87e7dce428d62fa8878a30d318

PUBLISHED_FROM=e69e298a51dbe0f9c47184169ecad06eef0676fc

PUBLISHED_FROM=98fb6c78d20a98dfba07ba6671bd51a394bbc4ca

Also amend api_net.js to use returned length.

PUBLISHED_FROM=38e15f9587edf28049c5b9e5f126b4db159910e8

PUBLISHED_FROM=578706e48a2c1fbbf5e9aaab3eba743e7d13fa61

PUBLISHED_FROM=9e345f2319141f20b89e28a2d29adba21ea213e1

Raised in previous commit by mistake

PUBLISHED_FROM=31a73fb610c34ed0c85d081bfa11a8067f216696

As required by the LWIP API

PUBLISHED_FROM=7bfc6d816aa69f8fdd7592ade48b2d52e2d4991a

PUBLISHED_FROM=32bda9e86a11cad3b908d211a1f7bc9d27312874

With different filesystem implementations and storage drivers, like grown-ups have :)
This is not currently used to add any new functionality, we still have
only one FS and driver on ESP8266 and ESP32; CC3200 has two: SPIFFS and SLFS.
This will be used soon to implement filesystems on additional SPI flash chips and SD cards.

PUBLISHED_FROM=293960fef82952c505e9b1925aac7724c7308362

PUBLISHED_FROM=0ffcd770535efa66ff1b6f9201f2caf832bd5055

PUBLISHED_FROM=657a53762ada0ab3fe715a15939eb510a637e37f

PUBLISHED_FROM=0ffcd770535efa66ff1b6f9201f2caf832bd5055

PUBLISHED_FROM=967a7ff3684e548ddbfe92365f7718a99e14d098

 - Move keep alive management up to the Mongoose library
 - Only outgoing control messgaes should reset keepalive timer
 - Add unit test

https://forum.mongoose-os.com/discussion/1155/mqtt-keep-alive-compliance-issue

PUBLISHED_FROM=f86e30744ded53a6f7f96afec066b4ff3b4372c0

This adds compile-time checks for format strings.

Fix issues exposed by this.

PUBLISHED_FROM=b9f820d8ad44fce9186dfdad4fe109fafa5371ce