word/edit: remap/rename priority levels

word/edit: remap/rename priority levels

Insert additional levels to distinguish within animal groups, such as
recent mapping of different species with various levels of notoriety.
Splits priority 2 and 3 into two options each:

	UPDATE word SET prio = prio + 1 WHERE prio > 2;

0 essential   → essential   : core terms and categorisation
1 basic       → ubiquitous  : beginner level words
2 common      → basic       : internationally known
              → common      : expected, readily recognisable
3 distinctive → distinctive : native names, popular genus
4 optional    → specialised : significant species in field
5 invisible   → rare        : expert distinction or knowledge
                invisible   : placeholder group, ignored

For future listings of people, it would map to Brian Buckley's hierarchy
of fame <https://briandbuckley.com/2017/08/07/a-hierarchy-of-fame/>:

1 = l8 Incredulity (Einstein, Shakespeare, Jesus, Batman)
2 = l7 Reassessment− (Joan of Arc, Bill Gates, Moses, Vader)
3 = l6 Hiccup− (Newton, Jobs, Lennon, Lancelot, Jabba)
4 = l5 Ambivalence (Elon Musk, Carl Sagan, Lovecraft, Boba Fett)
5 = l4 Hiccup+ (Randall Munroe, Shigeru Miyamoto, Sylvia Plath, Mothma)
6 = l3 Reassessment+ (Douglas Hofstadter, Carl Linnaeus, Kosh)
7 = l2 Explanation (notable not famous: Lu Xun, Jane Espenson, Sim Aloo)