Fengyan - add mods to solid slide routine (subaerial, etc)

[JimKirby]

Add the additions that were implemented for Kitimat study

[JimKirby]

Fengyan, We should get the solid slide modifications added to the main code, so that we can run the multiple slides in the Valdez benchmark (benchmark 7).

[fengyanshi]

I have added the multi-slide option in branch 'fyshi'. To use this option, define -DLANDSLIDE_COMPREHENSIVE. I don't make a pull request right now because we need to do two tests before merging. 1) an existing test for a single slide, to make sure the previous code is not interrupted by my modification. I shortened lots of long statements which are over 100 characters (troublesome for some compilers if without appropriate flags). 2) a multislide case, I will do it after the single slide test. You can clone the code and go to branch 'fyshi' to do the test.