Improved Point Shadow calculation to not need the lightProjectionMatrix.
It turned out that CubeMapArrays are only supported since OpenGL 4.0, so not in WebGL. Moving to Dual Paraboloid Mapping now.
Last Message was a false alarm - Multiple point and directional lights possible now.
 Error message was misinterpreted - seamingly samplerCube arrays ARE supported. Error occured due to usage of "continue" to skip block if lights are switched off - replacing by if-block solved the problem.
 Same error occured (unknowingly) on multiple directional lights - both are fixed now.
Moved direction calculation for point light shadow to vertex shader now - reduces number of possible point lights but should perform faster now.
removed pointLightProjection parameter as it is no longer used.