Include "ToOnlyContainType" method.

Turns Enum into List and repeats Assert.IsInstanceOfType for each item
in list.
Include "IsAllNotNull" method.

Turns enum into list and checks each item to not be null.  Also added
summaries for non-summarized methods and fixed a type in the
"ToNotContain" method.
Include "IsAllUnique" method

Also used LinQ to improve implementation of IsAllNotNull and
ToOnlyContainType methods.
Added tests for new methods.

Also converted all methods from using IEnumerable to ICollection.
include "IsEqual" method and test.

Also change all comments and summaries to correctly refer to
"collections" instead of "enumerables".
Include "IsEquivalent" method and test.

Also fix a bug where "IsEqual" failed if two collections had the same
element values in the same order, but were not referencing the same
object.
Include "IsNotEqual" and "IsNotEquivalent" methods and tests.
Include "IsSubsetOf" and "IsNotSubsetOf" methods and tests.
include "IsEqual" and "IsNotEqual" methods with comparer overload.

Also update all summaries to remove unused fields.  Tests for comparer
overload methods to come later.
Add tests for comparer overloaded methods

Also edited MinusComparer to include the necessary Compare method.
Standardize source code to follow specifications
Merge pull request #3 from hylasoft-usa/Implement-Collection-Extention-Methods-Issue-2

Implement collection extention methods issue 2