[luabind] Luabind exceptions

[Alexander G. <agl...@gm...>]

Hi, all!

Shouldn't all Luabind exceptions have common base class other than
std::exception (though that class should be derived from it)?

Sometimes I need to treat both luabind::error and luabind::cast_failed
in the same way, and want to handle other possible
std::exception-derived exceptions in another. Current situation forces
me to duplicate luabind-related exception handlers.

Thank you in advance,
Alexander.