Re-organize servenv flags a bit.

Flags are not enabled by default any more, but default
flags are very easy to enable. Next I will re-do the Port one.
Merge branch 'replication'
Second part of servenv rework.

lameduckMode flag is not local (not used anywhere else).
Allowing default flags and non-default flags to be used.
Always using default flags in our applications.
Merge branch 'master' into replication
parser: table_expression_list -> TableExprs
Merge branch 'parser'