userspace trawl: add parser aliases

[tinnus-napbus]

A draft of one approach to aliasing parsers to make them a bit easier.

What do you think of this approach @sigilante ?

also I'm not sure where the best place would be for these - I stuck them in a new lib just to put them somewhere

[sigilante]

Putting them in a /lib for consideration is great.

Then the core can be moved or integrated later if we want it in hoon or zuse.

[sigilante]

Yes, these look good. Maybe a ++whitespace too, around gaw or gay.