This commit allows user to select a few files and open only them using
imv-dir. When user opens just one file (typically by double-clicking on
it in a file manager), imv-dir will behave like it used to and open
open the whole directory.
I think this behavior is more reasonable doesn't add much complexity to
imv-dir. Now imv-dir conveniently accomodates the three use-cases which
I think must be quite common:
1. If user wants to cycle through all files in current directory, they
can just double click on one of them.
2. If the user wants to cycle through just a few specific files (say,
if they have many files in this directory and don't want to see them
all), they select them and hit Enter.
3. If the user wants to see just one file and doesn't care about cycling
through them, they just click on one file. The cycling is available,
but they don't have to use it.
For me, 1 and 2 were the main use-cases and to accomodate them I had to
switch between imv and imv-dir as default image viewers, which is rather
suboptimal. Now both are cheaply accomodated by imv-dir.
This changes make it more portable by removing bash dependency and not
using GNU-specific 'sort' syntax. Also this fixes issue with selected
image not being displayed first.
This includes the commands available in contrib/. It's enabled by
default.
I moved the manpage and desktop file to their regular locations to avoid
complicating the meson file too much. They won't be installed when you
disable the contrib commands.
