Recode org-is-habit-p to detect inheritance

Reimplementation of org-is-habit-p which takes inheritance of the
STYLE property into account, so it works with my habits.org file.

Additionally, compare the property case-insensitively so Habit and
habit both work.
Add a copy of latin-ltx.el TeX input with alternatives option

The original did not allow completion and remembering the choice
taken. By making a copy and altering the quail-define-package call in
this file this can be be resolved.

The name of the new input method must of course be different and it
needs to be registered.
Add url/cache to ignored pattern
Also archive CANCELLED items automatically
Add elfeed package