shortcuts: fixes and ammendments

CVCenter: fix globalShortcuts if a loaded setup doesn't contain global while server already running and active global shortcuts exist
CVCenterPreferences, CVCenterShortcutsEditor, OSCCommands,
CVCenterLoadDialog, CVCenterSpecsEditor: execute load/save upon hitting
'return'

Signed-off-by: Stefan Nussbaumer <st9fan@gmail.com>