update examples

[ch-nry]

replace "until" and "repeat" with "gemrepeat" add a lighting shader example since they have to be manually computed when using shaders add 3 opengl4 shader examples clean the glsl directory : move all shader in a dedicated directory and move images in the data directory various small clean in patch

[umlaeute]

thanks.

i've manually merged this (dropping the gemwin remote-display example, removing trailing whitespace from the shaders and cleaned up some help patches).