Make Ru not offer over-valuable sacrifices

Ru will now only offer sacrifices that exceed 160 piety by at most
10 piety.
Adjusting piety gain for Sacrifice Love and Sacrifice Artifice

Instead of dropping Sacrifice Love to negligible piety if you've already
sacrificed Summoning, it drops to 10 piety; ditto if you've already
sacrificed Evocations. If you've done both, then it's worth 1 piety,
since it could still make e.g. zot_tub a bit nastier. And scrolls of
summoning, too.

This removes any piety gain from skill in Summonings from Sacrifice
Love as well, since it doesn't actually zero out the points, meaning
you could get double piety gain from Summonings skill if you sacrificed
Love and then Arcana:Summonings.

Thanks to DrKe for the suggestion.
Amending previous commit which didn't get proper safety checks.
Pull god description functions into a new file

squashme
Pull gozag branch bribability adjectives into an array
More _describe_branch_bribability refactoring
Pull god-description toggle code into a common function
Pull god irritation descriptions into a function
More god description refactoring
Improve description of TSO's rN
Pull god misc info out of _detailed_god_description()
Add god wrath descriptions

In an attempt to despoilerify mechanics that don't really need
to be spoilers, divine dislikes and wrath effects are now in a
new screen. (Except for Xom, who is Very Special.) I've made an
effort to clarify which gods care about abandonment, which gods
are 'evil' and 'chaotic', and which god wrath effects scale with
XL. (Mostly the monster summoning ones.)

It might make sense to expand some of the detailed god
descriptions (e.g. the description of Zin's recite), now that
the second screen is somewhat less crowded.
Mention praying in altar descriptions (2371)
Describe the terrible wrath of Ru
Remove seen monsters from the minimap

They cluttered things up and really had no use for being there;
the minimap is for navigation, not... tactical memory?

Detected-but-not-seen monsters are still displayed on the minimap,
for easy eyeballing.
Fix invis + QUAD DAMAGE messenges
Tweak invisibility behaviour

Quaffing/evoking unknown invis sources will now give you the
status even when you're haloed; you can no longer quaff/evoke
known invis when glowing, since that is literally always useless.

Some cleanup should be done, per XXX comment
Fix confusing touch expiration (8967)
Give Demigods full stat control (Brannock, Bloax)

Trade their automatic stat-ups for a manual stat-up on every
2/3 levels. This takes them from gaining 22 stats by level 27
to only 18, which should be about an even trade overall.

More importantly, it focuses the race on its core positive design
differentiator ('good stats') and, perhaps, is more fun/distinct
for players. It's an experiment, but I don't think it'll break
anything.
fix some compiler warnings