Fix: Taking a screenshot now possible under windows without fiddling in a lua file.
Change: Screenshots get saved to a dedicated screenshot folder now, which can be changed in the config.
Add: Print some info when the user wants to take a screenshot, so he can see if and why it failed.

git-svn-id: http://corsix-th.googlecode.com/svn/trunk@1880 c39591fa-788f-11de-a72b-d90af8dea425