fix: replace preprocessor elif with else.
Fix reorder warning in PhysicsWrapper.
fix inverse sphere depth + better water
Merge branch 'master' into water_rendering_30
smaller spheres
fix shader reload, maintaining the shared shaders in the World #87

- creating only one glow::Shader instance per shared shader file
- the World is now is a singleton (seems reasonable), so that it's easier accessed from classes the need the lighting/ shared shaders
adopt cgsee's phong lighting to fit better with elemate's needs #87

- sunlight without direction
- phongLighting glsl function only takes parameters for current position/normal/material and secondary light source
some more shared shaders #87
fix #87, early bailing in shadow mapping

- wrong output values for fully in the shadow/light
- add early bail sample in the center of the testing area
generalize shadow and terrain drawing #57

- draw lightmap renamed to shadow map
- list elements to render in the terrain draw calls
Merge branch 'water_rendering_30' into terrainToParticles_57
Merge branch 'shadingIssues_87' into terrainToParticles_57

Conflicts:
	src/hand.cpp
	src/rendering/particlewaterstep.cpp
	src/rendering/renderer.cpp
	src/rendering/shadowmappingstep.cpp
	src/terrain/terrainshadows.cpp
	src/world.cpp
	src/world.h