Remove todo item about Thumbnail Managing Standard.
(tumme) <defgroup>: Change :group to `multimedia'.
(tumme-thumbnail-storage): Add choice `standard' for Thumbnail
Managing Standard.
(tumme-cmd-create-thumbnail-options): Use %w and %h instead of %s.
Fix dostring.
(tumme-cmd-create-temp-image-options): Use %w and %h instead of %x
and %y. Fix docstring.
(tumme-cmd-pngnq-program, tumme-cmd-pngcrush-program)
(tumme-cmd-create-standard-thumbnail-command): New user options.
(tumme-thumb-size): Set default to 128 if tumme-thumbnail-storage
is `standard'. Fix docstring.
(tumme-thumb-width, tumme-thumb-height): New user options.
(tumme-external-viewer): Try to find various viewers.
(tumme-get-thumbnail-image): Use `create-image' instead of
constructing the `image' structure.
(tumme-insert-thumbnail): Use `png' if tumme-thumbnail-storage is
`standard'.
(tumme-thumb-name): Add file name generation for standard storage.
Simplify code for other storages.
(tumme-thumb-name): Use width %w and height %h instead of size %s.
Add modification time %m and thumbnail-nq8 %q.
Use `tumme-cmd-create-standard-thumbnail-command' if
tumme-thumbnail-storage is `standard'.
(tumme-dired-insert-marked-thumbs): New autoload command.
(tumme-dired-after-readin-hook): New function.
(tumme-line-up-dynamic): Use `tumme-thumb-width' instead of
`tumme-thumb-size'.
(tumme-display-image): Replace size-x %x and size-y %y with
width %w and height %h.