The source files are only needed to build hmmlib.js, they needn't be
included in other projects.

Bugs fixed:
* marker offset should be correct now.
* after-text markers (-1 offset) now have type CATEGORY not HMML_CATEGORY
  which is consistent with the in-text ones.
* markers with parameters have proper .text and the marker.parameter
  doesn't start with "undefined" any more.