Added Color Picker plugin
Point, Flicker and Pulse light animation should now look almost exactly as seen in GZDoom.
Fixed a bug when editing thing properties in Visual mode didn't update visual thing.
Fixed incorrect doom-style walls shading when sector has "lightcolor" property set.
Fixed "Index was outside the bounds of the array in CalculateNormalsAndShading()" error.
GZDoomBuilder will now show error message prior to failing.
All dynamic light types are now rendered correctly.
Added Doom-style shading on walls (walls going from west to east are slightly darker than walls going from north to south)
Masked surfaces are now correctly lit by dynamic lights.
Fixed several bugs in models rendering.
