Units move too slow when in the shallows

[beherith]

Recently (inside of a year) movement calculation in shallow water was changed, and this has made units move much slower in water. This has a very detrimental effect on maps that rely on it (like Tabula, Tropical, Nation).

More info here: ​https://github.com/spring/spring/commit/9364b3cb0ab19b6a390e61d0e3934be000359e2e

Explanation by knorke: ​http://springrts.com/phpbb/viewtopic.php?p=512851#p512851

I propose a simple depthModMaxValue = 0.7 (units only slow to 0.7 of their max speed in water that is at least 20 deep)

depthModMinHeight = 4 (depth mod doesnt kick in water depth < 4)

depthModLinearCoeff =0.03 (every elmo waterdepth above 4 reduces speed by 0.03

[Bluestone]

Ok, cool, will do it when I get some time.