Folder.pm module for rendering folder previews.

Still have some glitches.

Conflicts:
	src/Factory.pm
limit recursive levels of folder rendering
set $ENV{BAPHO_LIBDIR} if not set
--help lists possible dbg flags (scans *.pm)
cosmetic changes
cache of folder rendering
use Carp; cosmetic changes

Conflicts:
	src/FileItr.pm
	src/main.pm
@INC fix (variable was defined outside BEGIN block)
Picture::print, works for folders too
identify jpg|png|tif|ppm

tmp
marks Folder.pm private methods
use the "best" pics to render folder preview
better fail message for gphoto2 command
fix cache of folders with spaces
Fix dangling tmpdir when creating video preview.

Sometimes mplayer generates more files, so we use `system "rm -r"`
instead of assuming the dir will be empty after we remove the first
frame.

Conflicts:
	src/Video.pm
add 'm4v' to list of known video extensions
when imporing, guess timestamp from the filename
fixes picture delete

Conflicts:
	src/View.pm
updating TODO