Add tags for searching to modules

[ericdill]

Description

In order to more effectively present our modules to users and/or larger communities (diffraction, imaging, fluorescence, etc...) one solution would be to add searchable tags to modules. This would allow the user to type in something like 'diffraction' and have only diffraction relevant modules pop up. It would also allow significantly more advanced sorting techniques to be used.

Notes

searching actually happens on line 214 of \VisTrails\vistrails\gui\common_widgets.py. From a quick glance, it looks like the searching is done on the name of the QItem that each module is represented as. The search signal/slot chain goes:

1. QSearchBox line 556 of common_widgets.py emits an executeSearch signal or an executeIncrementalSearch signal
2. Those signals are captured by QSearchTreeWindow on line 288 of \VisTrails\vistrails\gui\common_widgets.py and connected to the searchItemName method of that class.
3. searchItemName performs the search based on the name of the QItem

Potential Solution

This problem might be solved by adding another QSearchBox to the QSearchTreeWindow that does searches on tags and can have multiple tags separated by a comma, or something along those lines. Somewhere the tags need to get added to the QItems so that they can be searched.

[ericdill]

Also, their QSearchTreeWindow would be useful to ape some aspects of in my BrokerQueryWidget