Split off bitmap example as a first step towards separating the examples...

... into a bag of independent hackage packages.

I failed to build the full gloss-examples package due to some llvm problem and I'm preparing for helping out with a [beginners course](https://github.com/juliajansson/gitbeginner/blob/master/2014-12-29.md) using gloss and Haskell where installation problems should be avoided (and examples need not be so complex). 

I just tried separating the first example executable to start with. There may very well be a clear separation into just two example groups - if so, a hint would be appreciated.