Compile fixes

MinSG::loadTexture ---> MinSG::createTextureState
modified
Adapt to changes in Rendering::Texture.
Merge branch 'master' of https://github.com/PADrend/MinSG
Use project relative includes
added .project to .gitignore
added Renderer and Preprocessor
Preprocessor
mc
added ExternalNode, PartialRenderer and SurfelManager
compile fixes
Renderer
mc
implemented renderer and surfel manager
mc
async surfel creation
use mesh importer to load base64 encoded meshes
added ImportHandler + mc
added ImportHandler
some fixes and parameterization