refactored assembler and added catagory for RS,DRT,imm instructions these are the instructions that use a value in RT to differentiate between them
refactored assembler and added catagory for RS,DRT,imm instructions
these are the instructions that use a value in RT to differentiate between them

Signed-off-by: NoahTheGoodra <a2ed4e143de97a24244bfc14e4792995cd52b488@live.com>

jfmherokiller/SimpleMIPS.js,jfmherokiller/SimpleMIPS.js,jfmherokiller/SimpleMIPS.js