Log Message:
update to 1.0.5.5
changes:
More and improved folding and switching functionality for
	presentation mode (1.0.5.5).
Simple animations (1.0.5.5).
On-the-fly evaluation of computer algebra scripts (1.0.5.5).
Improved rendering speed of images based on plug-in for Imlib2 (1.0.5.5).
A simple thumbnail facility (1.0.5.5).
Documentation of tree API (partial) and structured editing (1.0.5.4).
Fixed some long standing bugs concerning cursor movement (1.0.5.4).
Implementation of structured cursor movement (1.0.5.4).
Enrichment of the Scheme API with routines for tree traversal (1.0.5.4).
Improved arrows and dashes for upcoming graphical mode(1.0.5.4).
Reorganized and consolidated tree API (1.0.5.3).
Started documentation of Scheme API (1.0.5.3).