Repair inline flag

Repair inline flag

In 9fca5d827d we attempted to deprecate the "inline=True" flag
and add a generative inline() method, however failed to include
any tests and the method was implemented incorrectly such that
it would get overwritten with the boolean flag immediately.

Rename the internal "inline" flag to "_inline" and add test
support both for the method as well as deprecated support
for the flag, including a fixture addition to assert the expected
value of the flag as it generally does not affect the
actual compiled SQL string.

Change-Id: I0450049f17f1f0d91e22d27f1a973a2b6c0e59f7