SBCL-style Unicode support: one character = one Unicode codepoint.

Allow one JSCL "character" object to be a surrogate pair (length-2 JS
string).
Unicode-aware implementations of most of the Characters dictionary.
CHAR-NAME and NAME-CHAR, for ASCII names.
Character comparisons, case sensitive.
Character comparisons, case insensitive.
Character case predicates.
Extend DIGIT-CHAR-P to include all HexDigit characters.
Fixing tabs/spaces.  (Oops.)
Merging from upstream.
Fix #111, error with docstrings containing single quotes
ESCAPE-STRING assumes the resulting string is going to be double-quoted,
and LAMBA-NAME/DOCSTRING-WRAPPER was only single quoting them.

A similar issue was present for function names with single quotes. These
should be read differently, i.e. FO'O => FO (QUOTE O), but until the
reader is fixed to deal with this I think allowing them in function
names makes more sense than failing with a strange error message
Merge pull request #113 from orodley/quotes-in-docstrings

Fix #111, error with docstrings containing single quotes
[doc] Some proposals for code organization and style
Merge pull request #108 from abeaumont/master

A proposal for code organization and style
Merge pull request #112 from kengruven/master

Character functions