Gnumeric 1.12.28

Morten:
	* Fuzzed file fixes.  [#761663] [#761727] [#762278]
	* Plug leaks.
	* Fix problems with ssconvert to lp/cplex formats.
	* Add sensitivity report to solver.
	* Fix bounds problem with cplex exporter.
	* Fix IMARCCOSH(1).
	* Add more tests for complex number evaluation.
	* Improve accuracy of IMLOG10.

--------------------------------------------------------------------------