Tidy P4Ruby's connection state management. P4ClientApi was accumulating
a lot of 'int' flags. This change combines them all into a bitmask with some
methods to encapsulate the manipulation of the mask.
I've also removed the code which worked around a very old and obscure
protocol bug in 2000.1/2000.2 servers. Anyone using a server that old
doesn't deserve the modern P4Ruby.
To test P4#server_case_sensitive? I have adapted the test suite so that
the server it runs uses the -C1 flag - so it's case-folding on all
platforms. The reason for this is that it enables the tests to succeed
on Windows and Mac OS where case-folding is the norm.