Add document_get_status() to get the tab colour for the document.
Use ui_update_tab_status() to update notebook tabs and open files
treeview items.
Avoid using GtkTreeIter struct as treeviews function arguments.
Remove unneeded arguments for treeviews_openfiles_add(),
notebook_new_tab().


git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@1053 ea778897-0a13-0410-b9d1-a72fbfd435f5