LAK package options keyword block that includes parameter for ramping down LAK release

[emorway-usgs]

The following suggestion was originally offered on the rniswon\MODSIM.git repo: The value of the parameter that controls when LAK release ramp-down begins to happen should be added as an input variable for greater flexibility for the user (currently it is hard-wired). To accomplish this, an options block with keywords should be added. Bear in mind that the tableinput option should be moved to the options block as well, but still maintain backward compatibility.

When coding this up, may want to do it on the 'develop' branch for distribution (merging) to other branches, including the 'modsim' (and perhaps the 'release') branches.