Autocomplete in the filters view, rearrangable tabs, and a few bugfixes

* Enabled some properties on wxAuiNotebook that lets you drag-order the tabs, and snap them out into side-by-side panes, which is pretty neat!  Sadly doesn't give you full VS style adjustment, and doesn't offer functionality to save your customised layout

* The text fields in the Filters view now autocomplete based on the data from the database, for quicker searching

* A couple of bugfixes related to selecting items in views when filters are enabled

* Tidied the filters panel layout slightly