Added simple parsing code, untested.

This includes a ParsingException class, a full implementation of the
parser.

Made token types a class attribute, for uniformity.
With this change, the tokenizer's usage of Enums to have an easily
printable type associated with each token is now the same as the
usage in the parser.
Added some simple tests for the parser.

Also began fixing flaws in the parser code revealed by the tests.
Added more sample manifest files for testing.

Includes an expansion of the tokenizer's testsuite to tokenize the new
manifests and verify the tokens produced. Added parser tests that
operate on the sample manifest files.
Merge branch 'feature/block-parser'