Catch more variables, first pass at string interpolation

String interpolation tests
Rename lex's testing parser

Add lex/parsing for :+-/*
Add sprites with args (not working)
Improve comment parsing
Bypass all variable substitution #3
Remove variable sub
Parsing of of sprite-file, image-width, image-height

Ability to print out filename of image
Make replace more robust when replacement is impossible
image-[width|height] only works with sprite-file