Property Grid: refactoring

[tomas-nestorovic]

There are two major cosmetical issues:

• Redundancy. To edit, for example, a 16-bit value, one must add an item for which the size of value has been declared to be 2 Bytes, and at the same time attach an 16-bit editor. There's no need to explicitly declare the size of the value for each single item - the size is given implicitly by the editor used to edit the value.
• Encapsulation. To distinguish between editors, their respective creation functions are encapsulated as static members of sealed structures. A better way is encapsulating them in namespaces.

[tomas-nestorovic]

With more than a year of no new activity, this issue can safely be closed.