LINQ Expression Trees Support

[aldrashan]

Adds support for building LINQ Expression trees by adding extension method to the Connector enum.

[aldrashan]

Usage:

Or statement of 2 filters:

var f1 = new Filter<Person>();
f1.By("Birth.Date", Operation.IsNotNull);
var f2 = new Filter<Person>();
f2.By("Birth.Date", Operation.GreaterThan, new DateTime(1980, 1, 1));
var orExpression = Connector.Or.Group<Person>(f1, f2).GetFilter();
var people = People.Where(orExpression);

Simple filter tree:

var orExpression = Connector.Or.Group(Connector.And.Group<Person>(f1, f2), Connector.And.Group<Person>(f3, f4)).GetFilter();