Make new class P4::Message for returning Error objects
to the user. Currently handles errors and warnings, but
could potentially be used for output too (might bloat
people's code though).
Essentially, if you're using a 2010.2 or later client,
or if you've set your api_level to 68 or higher, the
P4#errors and P4#warnings arrays will be populated
with P4::Message objects instead of strings. Users of
older API's, or those who set their api_level to 67
or lower in their scripts will get the old behaviour.
P4::Message objects have the following methods:
severity() - returns the severity
generic() - returns the generic code
to_s() - converts the message to a string
inspect() - returns a string showing the message details.
User-visible enhancement documented in p4rubynotes.txt