JISA: Jallenator Instruction Set Assembler

[Jallen]

I'd rather just focus on getting the assembler itself going with as much functionality as possible before adding another stage. At the moment I'm looking for the ability to split variables across the instruction (e.g. if you had your op code in two halves at either end of your bit layout or something). Also I want to add the ability to place the instruction keyword anywhere in the line rather than always at the start. I'd like to actually have a chat with a few people about what features they would find important for their instruction set and also the actual layout of the .yaml file. There is a lot that can be improved on and a lot will change over time. For now, it should work for simply laid out ISs but I don't want that to be the only case it will work in.