Check for IDL version >= 8.0

Add check for "recent" version of IDL, since some aspects of the code rely on
constructs introduced in or after this version.  Version 8.0 has been around
long enough (July 2010) that its requirement should not be a burden on those
wanting to use the distance-omnibus code base.

Check routine added, and modifications done to "front-line" routines to call
the check routine.  If an earler version of IDL is detected, execution halts.

	new file:   subroutines/omni_check_version.pro

	modified:   distance_omnibus.pro
	modified:   create_local_files/omni_assoc_catalog.pro
	modified:   create_local_files/omni_glimpse_emaf.pro
	modified:   create_local_files/omni_glimpse_postage.pro
	modified:   create_local_files/omni_glimpse_starsub.pro
	modified:   create_local_files/omni_grs_spectra_local.pro
	modified:   create_local_files/omni_import_velocity.pro
	modified:   create_local_files/omni_survey_postage.pro
Convert storage of map information into lists (requires IDL 8.0+)

Convert storage of map information from individual named variables into lists
(requires IDL 8.0+) to avoid excessive use of the Execute() command and the
feeling of spaghetti code.

Also, for the SURVEY structure, tabulate the number of pixels in each source,
and the peak flux density pixel value.  These are to be used with the surface
mass density computations.

	modified:   create_local_files/omni_assoc_catalog.pro
Convert storage of map information into lists (requires IDL 8.0+)

Convert storage of map information from individual named variables into list
(requires IDL 8.0+) to avoid excessive use of the Execute() command and the
feeling of spaghetti code.

	modified:   create_local_files/omni_import_velocity.pro
Convert storage of map information into lists (requires IDL 8.0+)

Convert storage of map information from individual named variables into list
(requires IDL 8.0+) to avoid excessive use of the Execute() command and the
feeling of spaghetti code.

	modified:   create_local_files/omni_assoc_catalog.pro
	modified:   create_local_files/omni_survey_postage.pro
Merge branch 'master' into release