Update combo points when the target changes or when the player zones in.

This fixes a bug where having 3 CPs up on one target then switching targets
causes Ovale to assume there are still 3 CPs up on the new target.
Reported by @Erizura in an Ovale rogue forum thread.

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@883 d5049fe3-3747-40f7-a4b5-f36d6801af5f