Detailed discussion: http://thread.gmane.org/gmane.lisp.babel.devel/56

Patch courtesy of Ariel Badichi.

Initial patch courtesy of Ariel Badichi.

Reported by Tobias Rittweiler: "Compiling BOM-VECTOR emits a
'type assertion too complex to check' note. The reason is that
(THE FOO (QUUX)) is actually of type (VALUES FOO &REST T) which
SBCL, at least for the moment, cannot cope well with."

- Rename RUN-TESTS to RUN and export it from BABEL-TESTS.
- New test CODE-CHAR-NILNESS checks whether we can encode all
  code points below BABEL:UNICODE-CHAR-CODE-LIMIT.
- TEST-UNICODE-ROUNDTRIP: don't try to encode non-characters.
- UTF8-ILLEGAL-CODE-POSITIONS: new test adapted from MGK's UTF8
  test suite.
- Disable a few tests for CCL: UTF-8B.* and CODE-CHAR-NILNESS.

- Add regression test: SHARP-BACKSLASH.3.

Patch courtesy of Andrey Moskvitin.

Be more conservative with base-string optimizations: only enable it on lisps that support it (SBCL for now)

Patch courtesy of Douglas Crosher.

renames and named-lambda for code clarity. abstract/concrete mappings don't inherit anymore, use a -factory prefix where approriate

- added regression test.