Added typed IsEqualTo and IsNotEqualTo chekcs to support : Check.That(4L).IsEqualTo(4) with implicit conversion from int to long.

Removed boolean specific equality checks which did not bring any value
Merge remote-tracking branch 'upstream/master'
Implemented IsNull and IsNotNull
Merge branch 'Add_Object_IsNull' of https://github.com/dupdob/NFluent into isNullIntegration

Conflicts:
	NFluent.Tests/EdgeCasesTest.cs
Updates the release note.