Added TemplateContentView

Fixed a bug in template selector that could lead to all instantiated
template selectors sharing a common collection.
Added ViewFor(T item) to TemplateSelector.
Added TemplateContentView a content view with a templateselector.
(Perfect for situations where you want to display different data types
in a single area based on  user selections (ie:  User choosable
widgets.).
Add an Exceptions Folder.
Added InvalidBindableObjectException.
Added NoDataTemplateMatchException.
Added xml doc comments
Removed unused using directive.

Removed unused directives
Moved the Selector function call to the correct location and commented
on why the move was made.
Fixed View/ViewCell bug

Fixed View/ViewCell bug in RepeaterView
Fixed View/ViewCell but in TemplateSelector
Added InvalidVisualObjectException
Added GridLayout utility class

Added new Folder: Behaviors
Added GridLayout class to simplify grids.
Supplies two attached properties:   RowHeights and ColumnWidths.  Each
one accepts a comma separated list of length values and converts them
into RowDefinitions and ColumnDefinitions appropiately.
Added CDATA to code example
Merge pull request #449 from Choran66/master

Added a ContentView with Template Selector support