Debug symbols

Cecil support of debugs symbols live in two assemblies, Mono.Cecil.Pdb.dll and Mono.Cecil.Mdb.dll. They are used to read and write symbol store files for .net, the pdb files, and for Mono, the mdb files.

• Mono.Cecil.Mdb is a purely managed assembly that will work on both .net and Mono, on any platform.
• Mono.Cecil.Pdb has a managed pdb reader, but a writer that uses COM interop. It means that you can use it to read pdb symbols everywhere, but that you need to run on windows to emit pdb files. The managed reader uses code from the CCI project.

From an API stand point, there are two ways of interacting with debug symbols. The easiest is to simply pass `True` to ReaderParameters.ReadSymbols or WriterParameters.WriteSymbols. Cecil will try to load the debug store support assembly depending on the runtime (pdb on .net, mdb on Mono) and read and write the appropriate symbols.

If you need more control, you can specify ReaderParameters.SymbolReaderProvider and WriterParameters.SymbolWriterProvider. Those interfaces control respectively the creation of a Mono.Cecil.Cil.ISymbolReader and a Mono.Cecil.Cil.ISymbolWriter specific to the module.