add first draft of ActorScroller example
draft 2 of ActorScroller example; still needs work
* removed QuantizePixels because it's unused
* make note that the "BitmapText requires ActorFrame for coloring" bug has existed for a while
* mention what offset actually is in TransformFunction
Allow Update and Draw functions to be turned off

allow nil to be passed as an argument to SetUpdateFunction and SetDrawFunction to turn off said functions.
Merge pull request #267 from sigatrev/Update-and-Draw

Allow Update and Draw functions to be turned off
fix ActorFrame diffusing and glowing children

When an ActorFrame's parent has a diffuse or glow, the ActorFrame uses
the static tempState in Actor::PreDraw(); When the ActorFrame draw's
it's children, those children also use tempState because their parent
has a diffuse( making their internalDiffuse not 1,1,1,1 ). If any child
is diffused it'll will change tempState, which will affect the
internalDiffuse given to the next child, and so on.

By determining the diffuse and glow to be passed to the children before
drawing any of them, any changes to tempState will not affect the
diffuse of subsequent children.
Merge pull request #269 from sigatrev/ActorFrame_diffuse

fix ActorFrame diffusing and glowing children
Fixed CreateMethodTable to create a new table even when something of that name exists, so that the previously existing one that might have been modified by a theme is removed when changing themes.
Merge branch 'master' of github.com:stepmania/stepmania