Critical Xflow fix.
Implemented Xflow operator overloading.

There can now be several operators with the same name.
Operators with matching input types is choosen.
If no operator matches, a detailed list of all operators
Merge branch 'xflow-overloading' into develop
Added an option for movement aware click handling. When TRUE a click event will not be triggered if the mouse has moved more than 4 pixels between the mousedown and mouseup events. Default is FALSE.
Added framework for shadowmapping for directional light by the model of the already implemented SM for spotlight
Added (experimental) tools to draw the shadowMaps using a modification of the original phong shader,
Hotfixed a bug that made ignore the position and direction of Light during ShadowMap calculation, TODO perhaps move calculation to shader...
 Standard Shadow Mapping working quite well for Spotlights now.
Standard Shadow Mapping for directional light now working partly, still needs an adaptive fallOfAngle for the Frustum.
Found a bug where the Farplane was set to 200 by a return statement at the beginning of the block, ignoring the rest... revise why (maybe merge error)
Added a function to create a XML3D.math.bbox out of a XML3DBox
Issue #62: Added a public interface to set the world space bounding box of an object
Light transformation revisited+refactored for renderlight; Directional Light now uses world-rotation too, ignoring translations
RenderLight refactored and fixed again; removed bugs in phong shader that occured only when using different light types; added first preparations for point light shadow maps
added CubeMap(still to improve) support for pointlight shadow mapping, aswell as cubeMapTextures and (hacky) cubeRenderTargets.
added a hacky shader for "displaying" the shadowmap for pointlights.
 fixed some minor errors here and there
backup-commit: CubeMap version causes some issues and may lack flexibility, trying another way now
Shadowmapping for pointlights now nearly working,
some issue remaining in depthcalculation in other than initial viewdirection, still uses CubeMaps, looking at flexibility later if issues occur
Merge branch 'develop' of https://github.com/xml3d/xml3d.js into develop
Basic Point Light Shadow Mapping finally working,
errors occured due to near plane offset for other than default direction AND default direction farplane potentially to small for other directions, for now pointlight farplane set to 2000 for testing purposes.
TODO change farplane for pointlight so that it automatically fits to the max of all direction far planes
add automatic fov calculation for directional light, then basic shadowmapping is finished
Following steps: add sampling for soft shadows, add advanced techniques for shadow mapping itself
Added automatic FallOfAngle calculation for Directional Light and automatic frustum calculation for Pointlights,
also removed some console.log commands for debugging
and added different default shadow biases for the different light types
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.