Split up source code

Move classes and functions to separate files. (No actual changes to the
code.)
Document Option + subclasses
Document Argument + subclasses
Make run.ceylon non-executable

Not sure why it was executable in the first place. Oops.
Add test.herd.snopts module
Add ant build files

Copied from ceylon.formatter, then adapted and trimmed down
substantially (notably removing all OSGi stuff).
Simplify build.xml
Implement Option.equals, hash, string

Needed for tests.
Add tests for parseOptions()