Fix several bugs when MEKE_GM_SRC_ALT is True, including corrections to two
dimensional rescaling factors, and optionally fix a bug that sets a limit only
on positive slopes but leaving negative slopes unlimited.  This bug is corrected
when the new runtime parameter MEKE_GM_SRC_ALT_SLOPE_BUG is false.  Additionally
there is a new runtime parameter MEKE_GM_SRC_ANSWER_DATE that specifies the use
of rotationally symmetric expressions for PE_release_h when it is set to
20240601 or higher, but it should be noted that rotational symmetry also
requires that MEKE_GM_SRC_ALT_SLOPE_BUG is false.  Four new checksum calls were
also added to verify the correctness of the calculation of MEKE%GM_src when
MEKE_GM_SRC_ALT and DEBUG are true.  By default, all answers are bitwise
identical but there are two new runtime parameters in some MOM_parameter_doc
files.