Exposes ViewCoverage from coverage_model
First pass at ViewCoverage implementation

Simple implementation of ViewCoverage - filtering parameters from an underlying SimplexCoverage.

Example added that creates a ViewCoverage
Support for loading ViewCoverage

Also another example - using ptypescov
Fixes some bugs that arose due to changes in master
Adds refresh to ViewCoverage.
Adds verification of passed parameters to functions calling _parameter_name_arg_to_params.  Increases ViewCoverage function alignment.
Adds coverage for SimplexCoverage.refresh().
Adds refresh() for SimplexCoverage and AbstractCoverage.

Ensures None type not present in return value for _parameter_name_arg_to_params