OSMF SVN

Adding a simple layout sample that demonstrates how to position an overlay bug over a video using a parallel element.

Adding a 'smoothing' property, parallel to the one we have on VideoElement.

PARB changes: rename LayoutRendererMode to LayoutMode. Set modes to be "none", "vertical" and "horizontal". Updating units tests and client code accordingly.

PARB changes: make calculateContainerSize @private.

PARB changes: changing LayoutProperties.snapToPixel to be true by default.

Adding missing TestVerticalAlign and TestHorizontalAlign classes.

PARB changes: splitting layout alignment property into verticalAlign, and horizontalAlign. Removing registrationPoint property, and its enumeration class. Adding VerticalAlign, and HorizontalAlign enumeration classes, and updating unit tests and client code accordingly.

Extending ASDocs

Separate RTMP and HTTP switching logic, via different metrics providers. Extract switching logic from HTTPNetStream into standalone switching rule based on download ratio. Make terminology a bit more consistent. Clean up APIs. Add tests for download ratio checks.

1. add multiple BootstrapInfo support
2. add fragment discontinuity support
3. modify unit tests accordingly