General:

Adds a new --option/-O command line flag which can be used to alter desired checker behavior. This option can be specified multiple times for several options, although as of this release, there is only one supported option (see notes in CF section below).

Changes to CF checkers (all versions):

Corrects "coordinate data variable" finding routines to correspond with CF Section 1.3 "Overview". Coordinate data variables now find both NUG "coordinate variables", which are variables with one dimension where the dimension has the same name as the variable, and variables referred to by the contents of the coordinates attribute in other variables.
Improves readability of error message for attributes which are improperly placed according to CF Appendix A's "Use" column.
Disables checking of Appendix A by default and only checks Appendix A if cf:enable_appendix_a_checks is specified in aforementioned -O/--option flags via the CLI.