Bump versions number for 4.4.3.
Moved routines under utilities folder.

(cherry picked from commit 3f496b494db66464d4dbfa634549987ebbbbf1b4)
Added isdiagonal routine.

(cherry picked from commit 49e53f92997f05fa612c173491149539b8073d04)
Added utilities/dseries subfolder in the path.
Updated NEWS for version 4.4.3 (list of bug fixes).

(cherry picked from commit b313ea4a00550d4084c7629870874f3660f3af67)