Fixed formatting issues on api docs.
Rewrote theme's API.

- Added the concept of "Parser" to parse JSON files into Templates.
- Made a package out of Theme.
Renamed internal functions of Theme. Improved inline documention.
Renamed Template names. Template is no longer an ABSMeta class.
Fixed test on frame loading.
Minor changes on documentation and README.
Made frame padding smaller in the example.
Added a resource for the theme tests.
Improved docs of viewer.