Better subset of commands converted

Still a lot of brokenness, but at least you can goto and quit as well as
simple scroll.
item-list properly takes domains and ranges

So, for example, the $ bind works properly now (`item-state read tag,0-.`)

A list like 0,1,tag,0,1 will resolve to global items 0 and 1 as well as
selected tag items 0 and 1.

Mildly tested =P
Fix backspace

Had this before, but lost it. Convert curses KEY_BACKSPACE into '\b'
that readline will recognize.
Bulk command/type registry
Update reader commands
Fixup basic completions, correct delimiters
Remove dead arg_transform reference
Make tag_by_item O(1) instead of O(n)
Remove dead func
Flush input before getting a key

We want a currently pressed key, not one queued up from seconds ago.