Attempting to fix issues in #2176

Try to tidy up the eclipse shaders so they're a little more GLSL120 compliant in the hope that it'll make Tichy's open source AMD driver work. Totally blind.

#2176 is the main thread for this.

*EDIT* - This is tidier than the original commit. It works and can probably be merged but it doesn't fix the original issue which appears to be caused by the open source drivers and I have no way of reproducing.