Removed functions for escaping or quoting single bytes.

These functions were considered to add too much unneeded complexity.
Renamed UTF8 sub-module functions, and fixed some inconsistencies with signedness.
Re-organized unit tests.

They were broken up into several files. One main unit test file, and one for each sub-module. The UTF8 sub-module still doesn't implement any tests.
Added unit test for UTF8 sub-module.

Some bugs were discovered and corrected as a result.