Updated single header for 2.0.3

--amend

Added futher usage instructions.

Added instructions for building and running the examples.

Bumped the version number.

Removed the conditional preventing the loading of a mesh if we haven'…

…t do so before. This should be a flag, rather relying on testing for initialisation.

Removed the conditional preventing the loading of a mesh if we haven'…

…t do so before. This should be a flag, rather relying on testing for initialisation.

Setting example to view from a different angle, not rendering as solid.

Fixed formatting and links.

Forcing at least version 2.8 of cmake.