mro UTF8 cleanup.

mro UTF8 cleanup.

This patch also duplicates existing mro tests with copies that use
Unicode in identifiers, to test the mro code.

Since those tests trigger it, it also fixes a bug in the parsing
of *{...}: If the first character inside the braces is a non-ASCII
Unicode identifier character, the inside is now implicitly quoted
if it is just an identifier (just as it is with ASCII identifiers),
instead of being parsed as a bareword that would violate strict subs.