bug 1505 - Disk-based join

Added a session variable to limit UM memory usage by that session.
Bug 5978 - crash with prepared statements

Make the checking of table type safer.
bug5451: recover idbbuild.sh
rollback to commit 66aa84f4baff1d5866cc4568dd36379b037385fe
Bug 5978 - crash with prepared statements

Extra check for table type for prepare statement, in case the "s"
structure is not initialized.
set exec bit
bump release
update automake stuff
Merge remote branch 'origin/develop' into feature/MySQL-5.6

Conflicts with new vars merged by hand.
Merge remote branch origin/develop into feature/MySQL-5.6