Adds general PropList.txt support for cl-unicode and HEX-DIGIT-P.

- Exports PROPLIST-P
- Exports HEX-DIGIT-P
- Adds tests for the Proplist slurping.
- (proplist-p c :whitespace) -> :white-space,
and :other-default-ignorable -> :other-default-ignorable-code-point
Adds BIDI mirroring glyph support to further cl-unicode compatibility.
Adds unicode-1-name support

- Exports SB-UNICODE:UNICODE-1-NAME
- Allows specification of characters by Unicode 1 name with UNICODE1_ prefix