Add ANTLR 3.5 and regenerate grammars. Begin to fix ensuing compilation problems.
NH-3251: Fixed compilation failures and then many test failures due to trying to convert non-terminals to roots.

(cherry picked from commit 30ec2177c2f85beab8f82b709822c6685413809c)
NH-3251: Fixed more test failures due to the root promotion bug.

(cherry picked from commit ccc5a09c9fa2968de5b90db7f11774128e8217f2)
NH-3251: Fixed not implemented exception relating to HQL parsing.

(cherry picked from commit fc2fdd730483bd14f04da5182c169fa5e0b6ebc0)
NH-3251: Removed a bunch of useless code.

(cherry picked from commit f1c74165be0ae3fd60f859a7b5513a52a18fe5a1)
NH-3251: Fixed the last two discriminator test failures.
Switch the HQL grammars to use the ANTLR CSharp3 target.
Merge branch 'NH-3251-3.4.x' into 3.4.x