Netbooks optimisation

Due to netbook displays have very low resolution height if Smuxi detects resolution height less then 768 pixels it will do the following:

• For GTK 2 - hide the toolbar and move the tabs to the right
• For GTK 3 - Hide the toolbar and move the toolbar elements as menus in the menubar

Option to manually show or hide the toolbar will be available in internal settings for both versions. However it won't be available in the normal settings.