catch up on half-physical damage docs

This is catching up on some things that were changed
in development years ago that Dave C. suggested be
documented.

For the record:
-The things that were evaluated and ruled out
are now documented in include/youprop.h so they don't
come up again.

- The things that were evaluated and deemed to be susceptible
to the intrinsic and thus led to a modification in the code
are listed below in this commit message.

Modifications:
- A crystal ball exploding on being applied
- Artifacts' blasting
- Being a fish out of water
- Being hit by Mjollnir on the return
- Being thwacked by an iron ball chained to you
- Boiling/freezing potions
- Broken wands
- Bumping head on ceiling by cursed levitation
- Burning (un)holy water
- Chest/door/tin traps
- Dipping a lit lamp into a potion of oil
- Exploding rings and wands (under all circumstances)
- Exploding spellbooks
- Falling downstairs
- Falling into a (spiked) pit
- Falling off or failing to mount a steed
- Falling on a sink while levitating
- Getting squished in a pit under a boulder
- Hitting your foot with a bullwhip
- Hitting yourself with your pick-axe
- Hooking yourself with a grappling hook
- iron-ball-pulling yourself out of a bear trap
- Jumping/Newton's-Thirding into something solid
- Kicking something that makes you go "Ouch!"
- Land mine explosion
- Sitting in a spiked pit
- Stinking cloud damage
- Thrown potion (bottle)
- Zapping yourself with a wand, horn or spell
- Jumping yourself out of a bear trap

doc/fixes35.0

@@ -4,6 +4,8 @@ $rcsfile: fixes35.0,v $ $Revision: 1.445 $ $Date: 2014/11/18 03:10:36 $
 General Fixes and Modified Features
 -----------------------------------
 change the dreaded "Stop eating?" to "Continue eating?" with default "no"
+fix half-physical damage intrinsic protection from a number of 
+	events and circumstances
 setmangry should not be called when a monster enters a bones region
 bad capitalization of msg when charging for something that catches light
 missing opthelp for use_inverse