Conversion of kernel classes to Doctrine DBAL

The title is insufficient to capture the scope of these updates. The conversion required lengthy testing, and a variety of other changes that cover the same space have been included:

- User passwords hashes now use bcrypt ("blowfish") for increased security
- Module update process now automatically performs schema updates
- Patchwork UTF-8 libraries added to implement a "Unicode all the way" approach
- SQL prepared statements and bound parameters implemented in core classes
- Unified preloads/preload.php file now used reducing the number of files involved
- Several improvements for some debugging tools

Note: running *composer update* is required for these changes as several packages were added and/or updated.