Switch to an open-source assembler

[flarn2006]

I wish I knew earlier that vasm existed. I didn't think any free tools existed for C166. Always nice to eliminate dependencies on proprietary software, plus it looks like this will work a lot better for my purposes anyway.

[flarn2006]

And it looks like the GNU assembler supports C166 as well; the documentation just isn't very good.

(Use ./configure --target=xc16x-none-elf when compiling the assembler.)