According to https://bugreports.qt-project.org/browse/QTBUG-13668, updating
ranges of data currently is not supported. Removing this code simplifies
the UAVO Browser.
Fixed comments and formatting.
Fixed bug by which the treeView model could change but the
UAVOBrowserTreeView was not aware of it.
Changed QModelIndex to reference the root node, instead of the
settings node. This makes no difference to the update scope
(see prior commit regarding QTreeView updates), but is more
logical to read.
Chase away bob and fred.
Revert "Changed QModelIndex to reference the root node, instead of the"

This reverts commit 5238aacf0916a8689aa9d2eef82fe6becd863b3f.
UAVOBrowser: Fixed bug by which the UAVOBrowser buttons would not toggle.
    This was caused by the deleted model still being the signal source for
    currentChanged.
Merge pull request #770 from kubark42/uavobrowser-qtreeview-simplification

Simplify UAVOBrowser data range checking.