Check user directory for pref files. [671]
Add command to toggle spell description. [1628]
Add support for graying dynamic menu items.
Gray out and disable some context menu items. [1776]
Force drop knowledge on first kill and use race flags to determine drop text. [1780]
Remove obsolete monster macros.
Fix squelch type names.
Merge pull request #272 from bensemmler/more-stuff

* Fixes more of 671 by checking the user directory and loading a file there if found; this allows the user to set up a custom pref.prf file that loads in addition to the one in lib/pref.
* Fixes 1628 by allowing the description to be toggled with ?. Default state is off.
 *Fixes 1776 and adds some functions to set the valid/enable state of dynamic menus.
* Fixes 1780 by forcing all drop flags on first kill and displaying only what is used by the game (lore->drop_item and lore->drop_gold are ignored now).
* Fixes issue with squelch type name (http://angband.oook.cz/forum/showpost.php?p=85439&postcount=251).