* Flash savings: getFileExtension() de-templated, saves 160 bytes
* Flash savings: several variables moved to rodata, RGB macro optimization (speed and can now be used to initialize rodata)
Result for Horus:
text data bss dec
1261182 808603 42020 2111805 before
1267149 803335 42124 2112608 after (data size also counts .sram section)
5kB saved in .data section (RAM and FLASH)
* Removed compiler warnings
* RGB() and ARGB() gtests added
* ARGB() optimized
