Added doc comments to all classes in Reko.Decompiler project.

#1354: Decompiler example is out of date.

Updated the documentation and provided a method `Decompiler.Create` to simplify
the creation of a Reko instance for simple scenarios.

Fix: _WINDOWS macro doesn't appear to be set anymore

Using _WIN32 and _WIN64 macros for the two Windows platforms.

Non-cs files

Feature: Add annotations to .Inc file (#1187)

Fix: RewriterTestBase

Over 50 unit tests weren't correctly testing!

Fix: build break

Feature: Procedure uses types + names of user and symbolic procedures.

Maintenance: mark data as mutable.

Enhancement: more ARM32 rewriters.