Bugfix: Fixed handling of non-image command line arguments
Accept URLs as command line arguments

Since I am already using gio, this feature does not come with any extra
costs (except possibly when used with static linking, where it might
increase the binary's size) but only changes one function call with
another.
Prefer local files over URIs

To prevent breaking compatibility, always prefer existing files over URI
interpretation.  For example, all files containing a colon cannot be read using
the g_file_new_for_commandline_arg command, because they are interpreted as an
URI with an unsupported scheme.

"Author: Title" is a common case where this would otherwise lead to problems.
Merge branch 'master' into redraw
Show clipping area in draw callback debug output