database changes

Added get() method to get a row by id, methods to rebuild or optimize
the index.
The snippets list doesn't load all columns automatically any more.
modified BuildableWidgetDecorator api.

Loads ui file and widget ids from class properties
Added EditDialog.set_editable()

In order to reuse the dialog for show actions.
minor changes to ui files
added more backup formats to gitignore
removed backup files
Allow edit dialog to be non-editable
removed dead code
Fixed clicompanion importer
Fixed timeouts handling
some pep8 & cosmetics
load snippets in idle callback
added treeview selection helpers, alternate search method for db
removed ignored sqlite file