Fix a bunch of errors in PO files (fuzzy file description, xgettext warnings and invalid new lines)

po/Makevars

@@ -8,7 +8,7 @@ subdir = po
 top_builddir = ..
 
 # These options get passed to xgettext.
-XGETTEXT_OPTIONS = --keyword=_ --keyword=N_
+XGETTEXT_OPTIONS = --keyword=_ --keyword=N_ --language=C++
 
 # This is the copyright holder that gets inserted into the header of the
 # $(DOMAIN).pot file.  Set this to the copyright holder of the surrounding