smurf: add in fixups for 2 SCUBA-2 observations.

SCUBA-2 observations 2012-10-04 scan 71 and 2013-03-29 scan 61 both
contain subscans where the telescope went very far off course.
The offending subscans will now be blanked out prior to
makemap running so that it doesn't try and make an extremely large
map, by adding them to smf_fix_metadata_scuba2.c
latexsupport: allow \_ in mathmode