Mark optional dependencies as such for packaging

[livanh]

Some dependencies are marked as optional in the README, but are configured as mandatory in Ubuntu and Arch packages. Assuming the README is right, this fixes the packages.

[actionless]

that was before plugin system was implemented

now it's possible to split materia to a separate package oomox-theme-materia

which will provide only /opt/oomox/plugins/theme_materia and will depend on oomox and inkscape, and other optional deps

what do you think?

[actionless]

however after/if this issue will be closed that will drop the dependency on inkscape:
nana-4/materia-theme#202

parallel actually used now not only in Materia, but also in gnome-colors-icons ( i need to update a README on that)

optipng is not really needed at all, theme generation can be easily changed to skip it if it's not installed

[actionless]

also as a third approach:

in arch linux it could be a good way to split each plugin and GUI app itself to separate packages and organize those packages into the group

but that could be a PITA for the packagers on other distros..

[actionless]

@LaurentTreguier what do you think?

[LaurentTreguier]

Splitting the RPM package into subpackages shouldn't pose any major problem, in fact if the installation process doesn't change and it's just about putting different files in different packages, then it should be pretty trivial to do

[actionless]

ok, i'll consider it repackaging like that then

1. i need to think of some elegant packaging scripts
   mb, to create ./packaging/install_plugin.sh <NAME>

2. i need to solve ./colors/base16 colorscheme directory which is a symlink to inside plugins directory.
   as a temporary workaround i can do something in install.sh script, to just copy it from plugin.
   but as a permanent solution i am thinking of extending the plugin api to allow plugins to ship their own colors directories

@livanh sorry, but i'll have to reject your changeset because of the discussion above

[livanh]

No problem. My main point was to avoid installing inkscape, so if that happens in some other way, I'll still be happy :-)

As a side note, I'm playing a little with debian packaging, so I can give some help there. I know it is possible to create many binary packages from one source package. I'll have to understand how you handle plugins and what the packages are supposed to contain, though.

[actionless]

in that case if you don't mind i can @mention when i'll be done with arch packaging, so you could implement the same change for debian packaging in the right way

[actionless]

i've created a ticket with the short summary so closing this one:
#129