Layout problems when using long tag names

[Jens-Koenen]

Long tag names cause layout issues, especially in the filter area of the browser, which has a fixed width.

[Jens-Koenen]

Added tooltips for tags with which the full name of the tag can be properly displayed. Besides that, changed the definition of the tags in the YAML files. Instead of two separate arrays for technique and domain specific tags, there is now a single list containing all tags. Every element of the tag list must have a name and a type field. Besides that, there is an optional abbreviation field. If the tag has an abbreviation, the abbreviation is shown in the colored box of the tag, and the actual name is used in the tooltip.