Enable the b-tree cursor objects overflow page-number cache, which is normally enabled only for incr-blob cursors, for all cursors.
Combine the various boolean fields of the BtCursor object into a single
bit-vector.  This allows setting or clearing more than one boolean at a
time and makes the overflow-pgno-cache branch faster than trunk on 
speedtest1.
Remove a stray C99-style comment.
Only use the direct-overflow-read optimization if all data from the overflow page in question is being read.
Experiments in picking better query plans, especially when the usage of one
index is a subset of another.
Avoid a (harmless) buffer overread that is possible on an OOM when
MEMSYS5 is engaged.
Make sure that an index that covers a proper superset of the WHERE clause
terms of some other index has a lower cost than the other index.
Also make sure an index that is a proper subset of some other index has a
higher cost than that other index.  Add test cases.
Remove an unnecessary conditional.
Merge in the latest changes and fixes from trunk.
Fix a compiler warning when SQLITE_DIRECT_OVERFLOW_READ is defined.
Minor performance enhancement and size reduction.
Remove an unnecessary conditional, replacing it with an assert().
Improvements to comments.
In the command-line shell, run set writable_schema before running the
".clone" command.
Fix a typo in the "Synopsis:" comment for the OP_VFilter opcode.
Use OP_Copy instead of OP_SCopy when moving results out of a subquery,
to prevent the subquery results from changing out from under the outer
query.  Fix for ticket [1e64dd782a126f48d78].
Ensure the "PRAGMA journal_mode=WAL" works coming from any other journal_mode
with ATTACH-ed databases.
Merge changes to the query planner that strive to ensure that any index 
usage that is a proper subset of some other index usage always has a slightly
higher cost.
Performance improvements when reading large blobs, especially if
SQLITE_DIRECT_OVERFLOW_READ is defined.
Modify the OR-clause handling so that it can safely deal with OR-clause 
with 17 or more terms.  Fix for ticket [10fb063b1179be53ea0b53bb].
Make sure column cache elements are cleared correctly when jumping over
code for key generation in a partial index. 
Fix for ticket [2ea3e9fe6379fc3f6].