add basic command-line interface (patch.lua)

document options
maybe deprecate options.unsafe

add delay slot warnings

add arithmetic (using %() syntax?)
add macros
implement push/pop/jpop as macros
be able to point to specific args of push/pop using variables
add file-reading directives (e.g. for automatic hook injection macros)
allow generation of shared object files (zelda overlays specifically)

don't require colons for +/- labels (this shouldn't break anything right?)

write tests for everything (try to focus on code paths)
test unary tokens
