Blender Git Loki

== Imbuf ==

The TIFF reader did error handling with assert which is a pretty bad
idea (tm).

This fixes the assert-crash, that the TIFF reader triggers, if one tries
to open a RAW-DV file within the compositor. (File extension is only
two characters long, which is enough for an assert... EVEN IF IT ISN'T
A TIFF FILE, WE ARE GOING TO OPEN. GRMBL)

Removed all other assertions and added proper error handling.
(using STDERR, where it belongs.)