Update greatsling description

(cherry picked from commit ccee437176b27dbfe7c33d9080772d72893a6bdb)
Nerf D:2 angels (Person Dyslexic)

(cherry picked from commit 90b15e8267961a2739c8893acdcbc3a0d734f1ab)
Add player lua to get the base skill value (unmodified by draining etc).

(cherry picked from commit c8494a13f39b015db5302ba12e035ffa2291583b)
Fix vaults with multiple KMASKs for the same glyph.

Combine them into a single mask, because later masks override earlier ones.
This is fixed more generally in 0.16-a0-185-g78d49c7.

Also give 'opaque' to the interior region of hangedman_elf_power_crystal,
so that it can place again (the same fix as 0.16-a0-186-g63fd307, but
using a single KMASK).