Improve item examination sidebar

Two aspects to this:

1. Added colored hinting to the action sidebar that appears when you examine an item. e.g., an empty gun will have the "W" in "wear" grayed out (can't do it at all); the "U" in "unload" red (can't do it in current state), and if the player has ammo; the "r" in "reload" in green (action is possible). Wield, drop, and throw are always green at present.

2. Added the ability to disassemble items from the examination screen.
2.1 What I was really after: the ability to tell in advance whether a given item can be disassembled, without having to jump through too many hoops :).