Experimental "PRAGMA data_version" command for detecting when another process
has changed the database file.
Adding test cases for the "PRAGMA data_version" command.
Update the PRAGMA data_version command so that it reponse to changes made
by a shared-cache database connection, and also to changes made by the same
database connection.  Add test cases to verify the new behavior.
Add the "PRAGMA data_version" command for checking to see if a database has
been modified.
Minor fixes and enhancements to the SQLITE_ENABLE_API_ARMOR functionality.
Support manually disabling overlapped file I/O for Windows sub-platforms other than Windows CE.