Add variable to control coverage width.

Add a TEST_VISTA_COVERAGE_SUBSET_DIR advanced variable.  It should be a file path
to a directory that contains routine files (*.m).  If routines are found,
the names of the routines in that directory should be used as the routines
for the line-by-line monitor to pay attention to.

It should also be used as the "Packages" argument to the mcov/cmcov files for CTests
calculation of coverage.

Change the files that have a call to startCoverage to accept this
variable.  This is more complicated for the RAS tests, as it needs to be
added to the test_suite_details information and passed as a command line
argument

OSEHRA-Id: http://issues.osehra.org/browse/OAT-136
Change-Id: Ib432782fc37171a0656ae4adbd3d097d5ced5eef