Add a 'raw data' viewer like PVRTexTool

[applecuckoo]

Basically something like this:

[bluescan]

This pvrtextool dialog is for wrapping existing raw data with the pvr header... tacentview does not yet support saving pvr files. However, it may be reasonable to allow display of 'raw' pixel data if you happen to know the pixel-format, dimensions, mipmaps etc. Will leave this request open but may not get to it for a while. Thx for the suggestion.