Rename.
Rework the structure of parsers a bit.

The current parser is the Classic parser. Put things into more
logical places and rename stuff.
Simplify and unexport parser methods.
Simplify even more.
Move things around in preparation for bigger changes.
Move around the parser and rename packages to allow for more
parsers to be implemented.

This is enabled by the extended PEG grammar in my fork of the
PEG parser.
Parser for a more structured query grammar.