Lower GC leakage.

WoW Lua still has some pretty bad GC.
Don't cast if channeling.

This will fix more than it will break.
Improve lag detection

Add the cycle time to lag calulation and set a decimal storage variable
for use in conditions.
Use global cycle time in rotation timer.
Add conditions.
Shadow Priest Rotation

Still needs cooldowns.
Add global lag variable.
Frost Death Knight

Needs work.