Graveyard, new scene

Added OnClick and Automatic modes for graveyards
Started tutorial_scene
Revised new scene
Added zombie cost

New UI element to show Mana
Revisions
Removed playmaker

Also added elementals package
Other changes
Removed playmaker
New speed mechanic

Zombies increase speed based on how many other zombies are nearby
House change

Disabled Navigation Static, added navmesh Obstacle component so nav
area is clear when house disappears
Refactored animations
Merge branch 'Mike's-changes'