Refactoring Pronsole to wrap print in a self.log method so that it can be reused and overriden by a web interface or any other non-conosole interface

To ensure safety, we make sure we set target temps to 0 before we exit
pronsole.

Presently, one might accidentally terminate a print with a CTR-D while
printing. Now we ask the user to confirm exiting if there is a print
going when they try to exit.

Protect the user from typos in setting the extruder temp by confirming
them with the user if they exceed 250.

Presently, when you connect to a printer using pronsole, one sees
something like:

uninitialized>start
uninitialized>Printer is now online
uninitialized>echo: External Reset
printer>Marlin 1.0.0 RC2
...

With a few carriage returns and some string hackery, we clean up
the output so that one sees:

No port specified - connecting to /dev/ttyACM0 at 115200bps
start
Printer is now online
External Reset
Marlin 1.0.0 RC2

Much cleaner!

The monitor command now:

* Has more pythonic code
* Limits precision of progress elements (12.3% instead of 12.347812...%)
* Uses a carriage return to have print progress replace the previous
  progress line.

For example:

Monitoring printer, use ^C to interrupt.
Updating values every 5.000000 seconds.
Print progress: 0.3%

Previously, the line "Print progress: 0.3%" was "Print progress: 0.2%",
etc.

* Prompts are now generated based off of string templates,
  for example: "%(bold)sT:%(extruder_temp_fancy)s %(progress_fancy)s
  >%(normal)s "

* We have a dictionary of prompt string templates for different
  situations.

* We have bold support for the prompt.

* We have extruder temperature support for the prompt.

* We have progress support for the prompt.

We replace the cmdloop function with a slightly modified version
to achieve standard unix shell behavior on keyboard interupts and EOF.

In order to do this, we consolidate handeling of printer status
with a Status class. The status class is updated by recvcb.

This has the side effect of simplifying the implementation of gettemp.

We also detect whether there is a heated build platform or not, and
don't display info about it if there isn't.

Prompt is now generated by a promptf() call for every cmdloop iteration.

Conflicts:

	pronsole.py

Patching do_load so that it updates the pronterface ui when the load command is used within pronterface

Conflicts:

	pronterface.py

In verbose mode (self.p.loud = True), the code actually sending
the G-code line prints this, too, so this was a duplicate.

Also remove the chdir() to pronterface.py directory

Also install webinterface deps and fix bug in configfile()

Make crash in estimation code not block file load.
Diable web interface by default.