Fix polymorph crashing, and teak the probabilities a bit.

This change will make polymorphing a bit more likely to occur.
The previous algorithm could often generate very narrow acceptable
level ranges which might not have been satisfied. After this
the range of possible polymorphs should be a bit wider.
Merge pull request #228 from non/topic/fix-polymorph

Fix polymorph crashing, and teak the probabilities a bit.
Fix disarming display on character sheet.
Add solid and hybrid wall options
Merge pull request #229 from fizzix/fizzix_merge

BoS fix and nerf GCV vault
Tidy up solid/hybrid wall options
Clean up the logic for hybrid and solid walls
Fix indentation
Fix up compiler warning
Fix lighting logic in cave.c
Merge Nick's background colour changes with fixes
trap.c: remove uses of FEAT_*
monster/mon-util: de-FEATurize
wizard.c: de-FEATurize
spells2.c: remove FEAT_*
More FEAT_* removal
The war continues.
Include names in the store config file.
remove FEAT_* from spells1.c
more FEAT_ removal