bugfix delete features #18
comments added
variance propagation for conversion from polar to cartesian coordinates #22
added exchange object for creating feature and changed create functions (now 1 function for alle feature types). #25
added exchange object for nominal data and comments.
fixes #26: after editing the group name in the filtered table view you can now select another feature
start implementation of plugin manager #8
Merge branch 'master' into task_benedikt

Conflicts:
	controller/controller.cpp
	openIndy.pro
xml import/export for the measurement config
nominals are now sorted next to their actual features. #17
update plugintreeviewmodel
bugfix delete feature (index out of range after a feature was deleted)
Merge branch 'master' into task_benedikt
Merge branch 'master' into task_Jens
Merge branch 'master' into task_Jens
start implementing a new function in SystemDbManager to query all available plugins
Merge branch 'openIndyXML' of https://github.com/OpenIndy/OpenIndy into openIndyXML
moved create feature function, sort function, add nominal to actual feature and other feature depending functions from controller to featureUpdater class. They are now static functions and can be called at several places
continue implementing plugin manager #8
add pluginDebugger to plugins/OiDefaultPlugin