Lamark

- Unified the lamark API function in lamark.py with the command line parser.

- The "latex" tag has now been renamed to "math".
- Added a new "latex" tag that accepts any arbitrary LaTeX.
- Added "displaymath" tag that renders equations to large indented images.
- Add "ref" and "ref-footer" for footnote support.
- Tags can now be nested, so "ref" tags can now contain "math" tags, etc.
- Lots of bugfixes.

- Default input is now stdin, and -f arg can be left off.
- Added better syntax error messages for malformed tags.
- Bugfixes.