Stratification v0.5 Release notes:

1) New draft of the map textures, and tweaks to lighting & specular. I'm learning as I go and expect to make another pass at the visuals in the future.
2) New water lane added along the bottom. This opens up an avenue for water units that doesn't involve getting in range of the middle cliffs.
3) Adjusted a mex either side down the bottom so that all bottom area mexes can be built by ship constructors.
4) Edited map_startboxes.lua so that the second AI spawn position is randomised between top and bottom with effectively equal likelihood.