Fix for two issues

Issue in Template class:
Replace only witespace characters instead of all non alfanumerical
characters. Else signs like ></= will all be replaced with _ and as a
result lose their distiction.

Issue in GdtTagLib:
Because the value wasn't encoded as HTML signs like < gave the browser
the wrong idea of an opening for a tag. This would result in lose of
displayed data.
Minor refactoring
Changed the way file fields are visualized in study editor.
Merge remote-tracking branch 'origin/refactoring'