Add simulator build to Travis config. Also, add the first trivial gcode test, which is feeded through stdin.
The output is not yet verified, only the exit code from the simulator.

Note: most (all?) non-trivial gcode files, like those are located under gcode_samples make the simulator to hang.
Having all gcode files as the test cases to run on Travis is the next goal.
simulator: add command line support to specify input file. Usage: ./tinyg.elf [input.gcode]

It's convenient for running the simulator inside GDB.
simulator: build with -fsanitize=address. This will make it much easier to find memory corruption bugs and non-initialized values access.

See more at

https://code.google.com/p/address-sanitizer/wiki/AddressSanitizer
https://developer.mozilla.org/en-US/docs/Mozilla/Testing/Firefox_and_Address_Sanitizer
http://blog.chromium.org/2011/06/testing-chromium-addresssanitizer-fast.html

Conflicts:
	firmware/tinyg/sim/Makefile