Fix issue 6899: Drag and drop designer uses first field after project reload
idx was not properly initialized at project load.
Show scroll bars for drag and drop attribute editor if necessary
Include project home in browser toplevel browser (implement #6955)
[API] add QgsProject::homePath()
[API] make QgsBrowserModel::reload() a public slot
Update Options dialog vertical tabs

- Icon-only mode now only shows vert. scrollbar as needed
- Icon-only mode is snapped to when splitter is near icons
- Splitter is adjusted for vert. scrollbar width, keeping it from covering icon-only mode icons
- Remove size grip for dialog
Merge pull request #377 from matthias-kuhn/attredit-load-idx

Fix issue 6899: Drag and drop designer uses first field after project re...
[API] Add method to QgsMapLayerRegistry to get layers using name