Merge branch 'loader'

This introduces the capability of loading l2 formatted source files.
The syntax for those is described here:
http://luke.redirectme.net/redmine/projects/l2e/wiki/LoaderSource

Please note that this method of loading data is very inefficient, but
convenient. Efficiency issues will be adressed by a binary file format
which mentioned source files can be compiled to.

Also, some representations have been adapted to a more link-friendly
structure and most of the configuration code in main has been moved to
their respective l2s files residing in /test-data/ .