Encode: Fixed a memory leak that occurred in the UTF-8 encoding.

The decode and encode methods allocated a SV for the result, this SV
is passed to the process_utf8() function which may croak() if the
CHECK flag has FB_CROAK set.
bump version number of Encode to _02
update perldelta with Encode fix
update AUTHORS
update Module::CoreList for RC2
bump version to RC2
bump Module::Corelist version