func.pm can 'use Package'

I have significantly modified func.pm, with two
specific changes:

1) It can now use package qualifications, like the
following:

ds-source = "func:Cricket::load('fifteen')"

It includes a 'use Package' statement in the statement
being eval'ed, so there is no further work on the part
of the user. I think this significantly enhances the
functionality of this module, because otherwise the
user was either limited to using functions already
included or had to modify the collector script to use
another package.

2) The return of eval() is now checked, and if $@ is
set to a value, Warn is called and nothing is returned.
This makes much more sense, and should make it easier
for users to debug their func() code.