Minor fixes and changes

-- Fixes incompatibility issues with MatrixGames Editor
-- DefaultEstab.xml and DefaultSettings.xml added to resources instead of having constant strings.
-- Changes newly created elements name format to "New #ID"
Adds accelerators, menus (menu bar), deletes default settings.

-- Adds accelerators for menu items (keyboard shortcuts):
---- Modifiers: ALT for source pane, CTRL for target pane.
---- For example, ALT+O opens a file in the source pane, ALT+S saves it; CTRL+O opens in target pane, CTRL+S saves it, etc.

-- New menus are added for edition and element creation.
-- Settings file is deleted, instead the Settings class initializes to default values.