make sure splash start and end markers have correct position

Compiler can change position of start/end splash markers or even optimize-out
them completely, because they are not used in the fw. 
Make them part of the splash data block, so their possition is always correct.
util/xbm2lbm was changed together with other c "images" to make it consitent.

src/general_menus.cpp

@@ -20,7 +20,10 @@
  */
 
 #include "menus.h"
+
+const pm_uchar sticks[] PROGMEM = {
 #include "sticks.lbm"
+};
 
 enum EnumTabDiag {
   e_Setup,