Add new test file e_walckpt.test. Still some tests to come.
Fix a buffer overread that might occur in analyze.c if SQLITE_ENABLE_STAT4 was defined.
Avoid a potential NULL pointer deference in the sqlite3_stmt_scanstatus()
logic.
Fix a (harmless) uninitialized variable reference in b-tree balancing for
auto-vacuumed tables with overflow pages.
Avoid accessing a single uninitialized byte when moving a rare 3-byte cell from an internal page to a leaf. This was not actually causing a problem, just a valgrind warning.
Add a missing mutex around calls to clear the KeyInfo cache when closing
a database connection.
Add missing mutex calls around a call to sqlite3SchemaGet() within sqlite3_open().
Add extra tests to e_walckpt.test.
Fix harmless compiler warning.
Increase the default minimum PMA size for multi-threaded sorting from 10x
the page size to 250x the page size.  Provide the SQLITE_SORTER_PMASZ
compile-time option to change this default.
Merge the KeyInfo cache mutex fix from trunk.