fixed indexing bug with 'redo' on the redo stack
fixed a z-indexing issue with the content panel
fixed a bug with tracking prototype constructor

When overriding or extending a prototype constructor,
to create a new prototype and constructor,
the constructor property for the new prototype was
not being set.
added getProp attribute for extras

Added a generic getProp property to the Object
prototype.

This is because I do not have a __methodMissing__,
Proxies, or equivalent, in Chrome stable and iOS,
for listening to lookups for properties which do not
exist.

So instead it is simulated through source code generation.
Implemented length and getProp for Range.
Strings now have quotes around them, and smoother transition changes.
undo / redo