Experimental code to prevent FTS indexes from growing indefinitely as the table is updated.
Fix a problem preventing delete markers from ever being removed from the FTS index.
Fix various problems to do with segment promotion. Add test file fts4growth2.test, containing tests to check that the FTS index does not grow indefinitely as the table is updated.
Fix a problem to do with loading the value of the FTS automerge setting from the database.
Do not search for promotable segments following an FTS 'optimize' operation or creation of a new segment on the oldest existing level.
Fix a problem with the handling of delete markers by automerge on large databases.
Merge latest trunk changes with this branch.
Fix a bug causing an incorrect segment size value to be stored if both an old and new FTS version performed work on the same incremental merge operation.
Add extra test to backcompat.test to ensure that old and new versions of FTS may work together on the same incremental merge operation.
Fixes to prevent an FTS index from growing indefinitely as the corresponding table is updated. Change the FTS 'automerge' option to allow the user to specify the number of segments that should be merged simultaneously by auto-merges.
Work around compilation issue with MSVC.
Fix harmless compiler warnings.
Fix a broken test case in fts4growth2.test.
Internally, use a 64-bit integers for segment level numbers.
Merge recent changes from trunk.