regular.mk: use lightdm instead of gdm3 for cinnamon

...and switch to cinnamon-regular metapackage in general:
the remaining blocker being gdm required by that and not
actually going to work (it used to start gnome-shell which
wouldn't work in that configuration either) is now fixed,
thanks cow@.

PS: plymouth is moved upstream, drop the dup.
regular.mk: add infinality font setup to e17

Looks better indeed, thanks cow@.
initial conf.d/p7.mk

Not as clean as it should be unfortunately,
main.mk has to be reworked to drop the crap...
README update

These have been proofread somewhat to correspond
to the current state of affairs; a missing one
was added for fonts feature.
0.9.16-alt1

- 1.0pre
gear-store-tags