Transcoder specializes the same way as everything else now.
Renamed *encoder_(c,t) to *encoding_(c,t).
Renamed encoding files to encoder.
Fixed up includes to match new filenames.
Renamed encoding/encoding_defs.* encoding.*.
Fixed up filename references in code.
Added structs to describe static and dynamic encodings.
Added missing UTFX_API.
Fixed compile error, added ctors to dynamic_encoding_s.
Temporarily ifdef 0ed out dynamic encoder and transcoder.
Encapsulated encoding/byte-order pairs.

- There's a huge performance regression. Maybe gcc can't optimize these out.
RelWithDebInfo build now works correctly.