Merge pull request #4 from sveale/master

Added "common" classes to template project
Make GM::Framework::find_path_in_hierarchy search for files too
Make GM::Framework::find_path_in_hierarchy spit more detailed exceptions
Make GM::Framework::TextureManager accept multiple resource paths
Add method GM::Application::add_extra_resource_paths
Add variable GM_ENGINE_RESOURCE_DIR to GmEngineConfig.cmake.in
Make template projects CMakeFile generate external_resource_paths.js
Make template project search for extra resource paths
Make GM::Framework::MeshManager accept multiple resource paths
Update external_resource_paths.json.in template with mesh path
Make GM::Application::Main::add_extra_resource_paths add mesh paths to mesh manahaer
Add new PNG image loader LodePNG
When loading PNGs via SOIL image, use LodePNG instead
Just fix some text alignment
Try to compute normals for heightmap
Make it possible to get a non-instanced copy of a VaoLayout
Make BufferVertexAttrib::compare(other) start on vertex index
Make it possible to get VaoLayout from VaoManager
Add missing file to all-include GM/Core/Core.h
Add file name to exception message, if *TemplaterParser throws an exception