Rewrite of the whole toolbar code. Now it is based on GtkActions and all elements can be added/removed/reordered using a simple XML file.
Add GeanyMenubuttonAction and GeanyEntryAction as GtkAction subclasses to have menu buttons and text entries in the toolbar.
Change the Goto line toolbar item back to a plain text entry again.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@3328 ea778897-0a13-0410-b9d1-a72fbfd435f5