Removed some solution items and class diagram
Replaced MsTest by NUnit, updated assembly information
Replace .Count().Should().Be() by .Should().HaveCount()
Split up all tests in EnumerableExtensionTests into their on files, grouped by the tested extension method
Moved all extensions methods into their own files (using a partial EnumerableExtensions class)
Fixed folder and namespace structure
Implemented MathHelper.Clamp as an extension method (IntegerExtensions.Clamp)
Inlined CollectionElementsPicker
Inlined CollectionIndexCalculator and IntegerExtensions
Inlined CollectionShuffler for Shuffle and Random methods.

Note:
  - Random will be optimized later.
  - Shuffle is lazy now
Corrected file naming
Moved extensions of IEnumerable<T> to Extensions/IEnumerable folder
Moved tests for extensions of IEnumerable<T> to Extensions/IEnumerable folder
Wrote test for NameValueCollection.ToDictionary
Implemented NameValueCollection.ToDictionary
Documentation for the ToDictionary method
Test for element equality
Test for converting an empty NameValueCollection
The [Test] attribute now always comes before the [ExpectedException] attribute
Test and implementation for NameValueCollection.ToKeyValuePairs method