#10 Better error messages with unsupported filetypes

[Bruno Postle]

(bug report transferred from hugin-ptx list, Stephan Hegel)

1. This link is to an ObjectVR, freepv should report that it doesn't support this format:

http://www.sphericalpanoramas.com/media/telescope.mov

FILE type:Unknown
state 7: internal error: invalid state after downloading to file

2. This QTVR file is encoded with cinepak rather than the more common JPEG, the error message is:

Jpeg decoding failed.

http://hugin.sourceforge.net/cinepak.mov