Merge two pairs of localizable strings in text_edit_window.c and text_common.c.
(GTK+ 3) Use gtk_widget_get_preferred_size instead of gtk_widget_size_request
Adjust the API checking macros (in configure) so I can easily maintain them.
(GTK+ 3) Use gtk_separator_new instead of gtk_vseparator_new
xfprot.c: fix number of columns error of macro_remove_table
Update all line-number comments in po files.
Set xfprot version to '2.4expl6'. Updated changelog.