Deduplicate miscast malmutation.
Replace demonspawn and temporary params with an enum.

This is much more readable in most contexts.
Remove an unneeded god check when using is_god_acting().

The asserts on is_god_acting guarantee that the god is valid, so we
don't need to worry about it. Also, clean up the asserts on
is_god_acting slightly to make it clearer they imply this.
Refactor and document some mutation code (PleasingFungus)
Unbrace
Zero out and stop training Shields on sac hand.

This does make the sacrifice more pronounced if you switch to TSO and
use divine shield, but leaving Ru isn't supposed to be easy.
Formatting.
Simplify TSO's Divine Shield.

It is now a simple additive effect on your SH. The strength of it just depends
on your Invocations skill when you invoke the ability. Because it isn't
affected by Shields skill any longer, it doesn't let you train Shields skill
with no shield in inventory now.

The formula might need some minor tweaking, but the SH granted doesn't seem
that different from the old formula in most reasonable situations.
Clean up player_shield_class().

The only actual change here is that previously Shields skill didn't give part
of its bonus if you were wearing a shield with a sufficiently negative
enchantment that it put you at 0 SH; now you get the normal bonus from
Shields skill whenever you are wearing a shield.
Fix ability text for Divine Shield (PleasingFungus).
Fix some bugs with tentacle placement.

The check for free adjacent space to the head monster in order to
place the tentacles was only checking that the locations are in-bounds
and don't have monsters. We now check that the locations are actually
habitable for the tentacles and check for any actor, since the player
could occupy one of these squares.
Update Shields skill description.
Add Patashu to CREDITS.txt.
Fix a reversed check (nagdon).
Ru redirect no longer identifies foe

[Changed patch to use the default parameter, which should be what is
needed here --wheals]
Restore some code accidentally merged away (|amethyst, #8978).

It disappeared in 682baf4c4