Add support for importing of metadata
RDFTreeCtrl: Handle model change events
MenuCtrl::askForFile: accept extensions filters
MenuCtrl::importMetaData: set ExtensionsFilters
query grid pane with fields add/remove first draft
small cleanup
Merge pull request #50 from asobolev/master

backbone for Query Tab

LGTM
MenuCtrl: use Opt.ofNullalbe for chooser results
MenuCtrl: askForFile takes a title param now

Make it more generic
MenuView: move "Import Metadata" to project menu

Also add trailing "..." to indicate it will open a dialog.
Merge pull request #49 from gicmo/md_import

Curde support for metadata import

LGTM
query execution in the query pane
table pane added + some refactoring
some cleanup
Merge pull request #53 from asobolev/master

First draft of query view components

LGTM
FileBrowser: stubs for view and ctrl
FileBrowser: BreadCrumb navigation and file service
FileBrowser: ListNavigation
FileBrowser: implementing FileAdapter and LocalFile
FileBrowser: Navigation update