Experimental changes to support a Win32 VSIX package flavor.
Make sure the sqlite3.h file occurs at the very top of the sqlite3.c
amalgamation.
Fix various harmless compiler warnings.  Change the "warnings.sh" script to
work with STAT4 instead of STAT3.
Additional test cases and requirements marks for the unlikely(),
likelihood() and instr() functions.
Add requirements marks.  No code changes.
Fix test numbering.
Add -no-undefined option when linking the shared libraries.
Fix a harmless compiler warning in lemon.c.
Enhance debugging support for the split amalgamation files when compiling with MSVC.
The split amalgamation option should be disabled by default.
Identify requirements text in the SQLITE_CONFIG_ documentation.  Fix a typo
(a duplicated word) in part of that documentation.  Add some requirements
marks for DETACH to the test scripts.  No code changes.
Fix Unicode character encoding issues on Windows.
Permit the creation of VSIX packages for Win32.
Fix harmless compiler warning.