Performance optimization in the applyAffinity() logic inside the VDBE.
Improved performance in the type handling of arithmetic operators in the VDBE.
Make the implementation of the sqlite3_aggregate_context() interface faster
for second an subsequent invocations.  This helps all aggregate functions to
perform better.
Changes to sqlite3ScratchMalloc() that make the entire memory allocation
interface a little faster and about 100 bytes smaller.
Fix a variable-declaration after code problem in btree.c.  Harmless in
GCC and CLANG but unacceptable for MSVC.
Another memory allocator performance optimization.
Faster implementation of the sqlite3ApiExit() routine.
Faster implementation of pcache1Fetch()
Patch the sqlite3PagerWrite() method in the Pager to run a bit faster.
The sqlite3VdbeChangeEncoding() routine goes about 3x faster if the
sqlite3VdbeMemTranslate() subroutine is not inlined.