Removed Typos

Hi,
I removed some typos and put in a method to read grayscale images (just for 4.3).
Sorry for the weird commits ;)
I made some example code for OpenGL 4.3 (even though that its probably rather 3.0)
We should discuss where to put it. 
Also I made some auxiliary files to simplify some things, but I don't really know where to put them either.

Then I tried to get OpenGL running with Windows. I noticed that the library names are all wrong.
Maybe we should introduce a global variable for the library name with @linux ? : @windows ?.
This works fine for OpenGL 1.0, but for higher versions I run into some problems, because you need to load to function pointers with glew. I gave up at some point, but it shouldn't be too difficult to get it to work.
Kind regards,
Simon