Add new interface to compiling cheetah templates.
Make Cheetah.cheetah_compile use Cheetah.compile
Remove tests/Unicode_test.py's dependence on Template.compile
tests/Template_test.py no longer depends on Template.compile
Remove Template.compile from tests/SyntaxAndOutput_test
Remove references to Template.compile in tests/Regressions_test.py
Remove Template.compile from tests/Cheps_test.py
Remove a lot of stuff from Cheetah.Template

This removes the following "features":
- preprocessors
- Template(src)
- Template.compile(src)
Improve coverage.
Requiring text for filename broke commandline script.