Intel hex support

[spth]

OpenRabbit should support the use of Intel hex (.ihx, .hex) files. It should try to detect if a supplied file is Intel hex vs. binary (maybe just checking the filename like other software does would be enough).

Intel hex is a common format. It is also the default output format of the Small Device C Compiler (SDCC), the main alternative to Dynamic C for Rabbit development.

[tomlogic]

One benefit would be the ability to skip over unused memory ranges. It might be possible to optimize the .bin loader to ignore blocks of all 0xFF, since that's what the flash erases to (I believe that's true for all of the products).

Best to integrate an existing Open Source .ihx parser instead of implementing from scratch.

[spth]

Intel hex parsers are small, and I don't know of a commonly used library.

I was considering just copying the one from stm8flash (https://github.com/vdudouyt/stm8flash) into OpenRabbit.

After all we know that that one handles Intel hex files from SDCC well.

[spth]

For project files, this is now implemented, using the ihex.h and ihex.c from stm8flash.