Implemented a dynamic amount system for battlecries.  Fix for Hero.copy()

Switched Old Murk-eye to the new Battlecry system
Made it so hero's weapons are sheathed at the end of a turn.

Closes #58
Making serets more regular.

All secrets surrounding attacking are now bound to the same event
Previously, event ordering was broken.

Also fixed a bug with Mad Scientist where the minion was killed on
its own turn.  Closes #57
Merge pull request #16 from danielyule/master

Merge