Build AVRootloader images from the commend line.

AvrBuild.bat calls the assembler for each bootloader image. Added a new Mini MWC bootloader image. the current images are:

- AVRootloader_AQUASTAR.hex
- AVRootloader_RX3S_V1V2V3_AILR_OUT.hex
- AVRootloader_MINI_MWC_AILR_OUT.hex

AQUASTAR and AVRootloader_RX3S_V1V2V3_AILR_OUT are byte identical to the build via AVRStudio. MINI_MWC_AILR_OUT is new.