Preferences: Item list: Add column for change font size
File list: Column editor: Add ability to save font size
Preferences: Display: Add option for allowing multiple instances.
File list, Owner column: use saved font size
Plugin base: Column editor extension: Add get_font_size method
Accelerator group: Test for keyval validity before connecting.
DBus interface: Renamed classes.
Created DBus common module.

Purpose of this module is allow operations on DBus without
having to depend on module imports and system support.
Main window: Use new DBus common module.
Plugins: File list: Fix link dialog placing keyboard shortcut in
destination.
Makefile: Detect working directory based on makefile location.
Updated language template.
Main window: Increased version number.
Merge pull request #13 from ArseniyK/font_size

Create option to customize font size for each column.
Merge branch 'master' of github.com:MeanEYE/Sunflower into release
DBus infterface: Add missing imports.
Updated language template to include column font size feature.
DBus interface: Fix inheritance problem.
Updated Polish translation
Merge branch 'release' into develop.