fix #2251 - M-5 operation with number_pad:2

fix #2251 - M-5 operation with number_pad:2

     From a bug report, using Alt+5 when number_pad mode
is set to MSDOS compatibility (where Alt+5 is supposed to function as the
'G' movement prefix) didn't work correctly.  The code that did M-5 to G
conversion was being executed after the code which should have gotten G's
direction, resulting in strange behavior, probably using stale values for
u.dx and u.dy.  (With current dev code, I evidently had u.dx==0 && u.dy==0
so was getting "You can't get there from here..." which is actually pretty
amusing in the current context.  3.4.3 didn't have that feedback so I'm
not sure what happened in it; possibly just silent refusal to move.)