for name consistency.

.... DataContractSerialization to XElement.ToString(). This breaks the
storage format's dependency on the object model.

Most fixes are about code style.

Major changes are in:
1. the algorithm to determine if type is apparent in creation or conversion methods.
2. option serialization/deserialization.

I'd overlooked the fact that !isChecked enforces `use explicit type` and
hadn't stored enforcement level values then. This fixes the bug.

Rename several internal types appropriately. Update file names to match
them. etc.

Adding Enforcement Levels to each `use var` option. Enforcement levels are: None, Info, Warning and Error.

To do:
unit tests need to be unbroken
refactoring to base classes and to be more generic
fix xaml styling and remove any hardcoded values.
fix up todo comments in code

Remove UseTabOnlyForIndentation since this is a public option & there
are no testcases for this option. With the changes the option is no
longer used making it obsolete. Fix the broken testcase which was
asserting the undesired behavior

CR: jasonmal;joshs;jaredpar;hechang (changeset 1412012)