Rename TI HAL files.
Refactor TI GPIO HAL.
Modify TI startup and syscall to match common linker script.
Fix arduino GPIO example to new GPIO HAL.
Add functions in TI and ST GPIO HAL.
Add UART support for TI :
 - Simple RX/TX seems to work;
 - Hardware control flow is not tested yet;
 - Callback is not implemented yet.
Change UART number in uart_example to be compatible with TI lm4f120xl.