Update for WOW 4.1

This patch added an extra parameter to COMBAT_LOG_EVENT_UNFILTERED.
Update for WoW 4.2.0

This patch adds a further two parameters to COMBAT_LOG_EVENT_UNFILTERED.
Allow storing up to 90 levels of monsters
Update readme and toc for 5.0.4
Convert unnecessary globals to locals

This is of some variables which don't need to be global.
Convert all calls to getglobal to use the _G table

getglobal() has been deprecated since 4.0. It's possible it may go away
entirely at some point.
Adjust function signatures to use the standard arguments

This isn't strictly necessary, but it's always a good idea to follow the
standard conventions.
Dead code elimination

Remove a couple of obsolete bits. No idea how one function came to be
defined twice.
Rationalise loading

Load on ADDON_LOADED, and remove unnecessary check from OnEvent
Don't bother registering for PLAYER_XP_UPDATE

It was only used for debugging purposes at this point.
Track environmental deaths

Falling, lava, fatigue, drowning, etc
Remove KillLogLoadingFrame_OnUpdate

This was only required to reset lastHitOtherToSelf after combat ended.
Now that we track environmental damage, that variable is reset when
necessary so this OnUpdate is no longer needed.

Consequently, we no longer need to listen to the begin/end combat
events.
Remove KillLogLoadingFrame entirely

Since we're no longer using the OnUpdate handler, there's no longer any
need to have a frame that's invisible when shown. Data loading is now
performed by the main frame, and the loading frame removed.
Update toc and readme for 5.0.5