Sort db objects in Database Structure tab by their name

Conflicts:
	src/DbStructureModel.cpp
ExportCsvDialog: Set table selection to current table in Browse Data tab

When called while the Browse Data tab of the main window is selected
also select the current table or view in the ExportCsvDialog.

Sort the table names in the combobox of the ExportCsvDialog.

Conflicts:
	src/ExportCsvDialog.cpp
Clear the tree widget in the Structure tab when after closing a DB

Clear the tree widget in the 'Database Structure' tab of the main window
after closing a database.
See issue #44.
Update the recordset label in the Browse tab after closing a DB

Reset the recordset label in the Browse Data tab of the main window
after closing a DB file.
See issue #44.
Fix a startup crash

dunno really know whats different here to master branch
grammar: fix column constrain

DEFAULT also takes quoted literals
grammar: forgot to update the AST treewalker too
release: push version to 3.0.3