Image fole formats support

[rvt]

Due to Cairo we currently can only load the PNG file format.
We need to have support in lcviewernoqt to load other image formats.

At this point I don't want to bluntly import Qt in this lib due to it's enormous dependencies and I rather would like to find a 'smaller' library. We don't need transformations (I think) only beable to show a image format in a Cairo surface,