Projectkk2glider/flash savings (#4199)

* 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

radio/src/gui/480x272/widgets/text.cpp

@@ -34,7 +34,7 @@ class TextWidget: public Widget
 };
 
 const ZoneOption TextWidget::options[] = {
-  { "Text", ZoneOption::String, OPTION_VALUE_STRING("\015\347\0\14\377\376\373\364") },
+  { "Text", ZoneOption::String, OPTION_VALUE_STRING('\15', '\347', '\0', '\14', '\377', '\376', '\373', '\364') },
   { "Color", ZoneOption::Color, OPTION_VALUE_UNSIGNED(RED) },
   { "Size", ZoneOption::TextSize, OPTION_VALUE_UNSIGNED(0) },
   { NULL, ZoneOption::Bool }