Redesign equality comparison logic

[dupdob]

NFluent should provide a flexible customisation logic for equality comparison.

Expected Behavior

NFluent should provide:

1. Value based equality logic for built-in types that lack an Equals overload (eg: Arrays, List<>...)
2. The possibility (for the user) to provide custom comparison logic for any type/interface
3. The possibility to support context (i.e. for one or more check) specific equal logic.

Current Behavior

As of V2.xx, NFluent provides the possibility to choose between three different comparison logic, without any customisation option.

Context

This enhancement was identified while working on #307 .