Fix assigning Flowing Water (regression from 6b00a3430d080ecf0b47ed0e13b...

...e535b7f2d5eef)

when rendering WITH water (-nowater not set) the assignBlock water case did not hit
and ended in the default else tree, which was only supposed to happen for doublesteps.
Flowing water has a "col" value, depending on its height, so we did hit the
sandstone & wood & cobblestone doublestep case, which is why only height(col 1&2&3)  flowing water
was replaced and the "low" flowing water not.

NOTE: also tested -nowater, still works
Images show the bug (without patch)

![mcmap-bug](https://cloud.githubusercontent.com/assets/775794/3634091/975c9a12-0f15-11e4-9e3a-8a1e88bf3368.png)
![mcmap-bug_orig](https://cloud.githubusercontent.com/assets/775794/3634092/975d8030-0f15-11e4-88b8-eb163302bfa9.png)