Added simple version of new tokenizer -- completely untested.
Simplified the action definition/constructor.

Because of the line->block transition in the language, action objects
can't be built out of lines. Instead, an action will take a command
list as a direct argument to its constructor.
Added docstring to enum constructor.
Cleanup of tokenize.py

Added comments throughout, better encapsulated functionality in
tokenize_stream(), fixed several typos in the state machine, and
made the enums more uniform.
Cleanup in the manifest execution package.

Removed the line and manifest modules, switched the sample manifest
to the new manifest format.
Added nosetest support to the lib package.

In order to be scanned by nosetests, packages need to be identified as
such by an __init__.py file. Here we add these to the lib package and
subpackages.
Added tests for the enum utility.

These are simple tests that verify that the behavior of Enum objects
remains as expected. This mostly protects against future, unplanned
changes that may break extensions of python-SALVE which use Enums.