MenuCtrl: use system menu bar on OSX
Merge pull request #42 from gicmo/osx_menu

MenuCtrl: use system menu bar on OSX

Nice, thanks
Config: absolute paths in project config file

This fixes #43 by removing the file paths from the system and project config files.

For old config files it might be necessary to delete the paths manually in some cases.
Merge pull request #44 from stoewer/gndata-editor-43

Config: absolute paths in project config file
Main Window: add tabs to main panel

Fixes #46
Merge pull request #47 from mpsonntag/gndata-editor-46

Main Window: add tabs to main panel