Support integer type
Remove redundant assignment
Support rect() type
Merge pull request #44 from dstockwell/integer-type

Support integer type
Merge pull request #46 from dstockwell/rect-type

Support rect() type
Fix line length in test-parent.html
Remove ClonedAnimation
Remove unused house-script.js
TimedItem.parentGroup should be an AnimationGroup, not a TimedItem

TimedItem attempts to use the following methods and properties of its
parentGroup member.
- iterationTime
- paused
- _childrenStateModified()
- type
- remove()
- indexOf()
- _addChild()

Of these, only the first two are provided by TimedItem. The others are added
only by AnimationGroup.
Make use of TimedItem._effectiveParentTime
Make use of ParGroup for DEFAULT_GROUP
Merge pull request #48 from steveblock/timeSourcesCleanup

Time sources cleanup
let length interpolation be independent of the expected length types
let length addition be independent of the expected length types
remove explicit initialization for zero point
Remove explicit initialization from toCssValue and fix bug in default interpolation case.
replace 'percent' label with '%' in length objects.
replaced length toCssValue with generic version
Make fromCssValue generic.
review changes