Roadmap towards Babylon.js 4.1.0

[x] High level objectives

• Update to Babylon.js 4.1.0
  • Core library
  • glTF loader
  • Inspector
  • Materials library
  • Procedural textures library
• Improve Inspector v2.0
• Improve feature support:
  • Animated skeletons
  • Shadows
  • Special FX

[x] April - November 2020

• Keep BabylonCpp core library in sync with 4.2.0 alpha and beta versions

[x] March 2020

• Finish porting BabylonCpp core library to 4.1.0
• Add class for reading and parsing the MTL file bundled with the obj file.