Google test support & Unit test refactor

add common/makefiles/gtest.mk
add checking dependency in fresh repo clone
fix segfault & stack smashing in serial calc project
move serial calc project unittest to gtes
avoid recompiling gtest library every time running make check
integrate build error code in project_manager.sh

migrate SerialDebugPrint api to non-macro, restructure i2c-console parser

change SerialDebugPrint* api & test src
move i2c-console parser to module & callback management
GPS breakout board to output to softserial

matured C support & new mk files structure

Software Serial C support upto 115200 for TX (RX isn't stable so it's dropped)
Support Arduino IDE framework (Arduino Makefile)
skeleton.mk is one-stop .mk for all projects, include it at the end of project's makefile
create libutils.a

I2C console, GPS parser, Simple calculator

Projects included in this relsease:

• I2C console
• GPS NMEA data parser
• Simple calculator