RLE for greyscale lcd (gives more firmware space!) (#1142)

* use RLE encodes bitmaps on 212x64 pixel radios

* fix model image display
fix icon display

* implement RLE bitmaps in companion for splash image on 212x64 radios
reserve 3kB for RLE bitmaps in firmware

* fix size check

* use defines instead of magic numbers

* fix display of splash screens on 212x64 radios

* add warning message if compressed image is larger than the reserved space

radio/src/gui/212x64/bmp.cpp

@@ -204,6 +204,10 @@ bool loadModelBitmap(char * name, uint8_t * bitmap)
   }
 
   // In all error cases, we set the default logo
-  memcpy(bitmap, logo_taranis, MODEL_BITMAP_SIZE);
+  RleBitmap pic(logo_taranis, 0);
+  *bitmap++ = pic.getWidth();
+  *bitmap++ = pic.getRawRows();
+  for(int i=0; i < MODEL_BITMAP_SIZE-2; i++)
+    *bitmap++ = pic.getNext();
   return false;
 }