[GTKUI] Reorganise layout of tab items and add Tracker tab

 * Changed layout of Status, Details and Options tabs.
 * Moved the Tracker translations to ui.common.
 * Created a new Trackers tab.
 * Added State to progressbar.
 * Translate State in piecesbar.
[GTKUI] Move Piece colour chooser below checkbox
[GTKUI] Remove icons from Tabs
[GTKUI] Change tabs from top to left side
[GTKUI] Tidyup Preferences Dialog

 * Remove unnessary page headers to save space
 * Reordered pages to be lightly grouped
 * Other changes to utilise space better
 * Fixed the plugin info panel collapsing on startup
[GTKUI] Convert the appindicator option into a radio button
[GTKUI] Move 'Add Dialog' prefs to Download tab

Also includes more tweaks to layout for consistency and creating space.