Add HAL_<MCU> option and -std=gnu<11> to gcc command line

Add options -std=??? and -DHAL<MCU> to gnu compiler. Gcc will compile
with -std=gnu11 and g++ with -std=gnu++11. The option HAL_<MCU> enable
Hardware Abstraction Layer to be selected in compile time.
Fix compile warning about redefinitions of true/false
Disable timers 2, 4 and 5

This timers must be reserved to use with IEEE 802.15.4 and save power.
Add ATMEL LwMesh Network Stack Library