Mark this as a developer release.
Added an internal escape hatch to completely disable exception handling.
Start adding a better replacement for %code blocks.

%code blocks disable all input/output customization performed
by XS++ typemaps; this is probably useful in some cases, and can't
be changed for backwards compatibility, but having a working
alternative seems a good idea (and is required for attribute
accessor generation with complex typemaps).
Unbreak attribute accessor generation with complex typemaps.

Tested with code using %output_list in a complex typemap, will
add proper tests later.