glsl-out: More glsl versions (#191)

* Added support for glsl core version up to 400

* Added 330 to the list supported versions

* Added links to all extensions and fixed a extension being wrongfully activated

* Cleanup and check for image formats

* Removed useless extension and location on layout

* Added support for external functions and fixed global names

* Typefier allow Scalars in distance and length

* Addressed comments

* Fixed extension appearing after body

* Fixed entry point not being generated