bdr: mergme: Lower loglevels
wal_decoding: mergme: lower log levels
wal_decoding: mergme: Use newer xmin horizon for hot search if possible
wal_decoding: update pg_xlog_wait_* to CHECK_FOR_INTERRUPTS
isolationtester: squashed merge of Abhijit's changes

* Run global setup/teardown on all given conninfos
* A revised set of tests
* Don't expect the wrong result
* A test to ensure that rows show up in commit order
* Put one inserting session onto d2
* Add comment
* An insert-insert conflict
* Allow conninfos to be marked as readonly
* An extension of order.spec to standby servers, from Craig
* Switch to "DROP TABLE IF EXISTS" at startup
* insert-insert isn't supported, but it needs to wait longer anyway
* Switch to accepting conninfos on the command line
wal_decoding: mergme: track end lsn
wal_decoding: test_decoding: mergme: track end lsn
wal_decoding: test_logical_decoding: track end lsn
bdr: mergme: track end lsn
Cleaner, transactional statistics updates