Conversion of kernel classes to Doctrine DBAL

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. (see this info to learn more about Composer, and how to install it. There is also this good article here)

You can merge this Pull Request by running
git pull https://github.com/geekwright/XoopsCore master
Or view, comment on, or merge it at:

https://github.com/XOOPS/XoopsCore/pull/42

Commit Summary
- Add cURL to the recommended php extension list
- Doctrine conversions, and Bcrypt ("Blowfish") password encryption.
- Schema conversions comments and images modules
- Fix a few inssues introduced in doctrine conversion
- Implement a unified preload file in some modules
- Allow absolute urls in button links
- Add RotatingFileHandler option for logs versioned by date
- Doctrine conversion missed earlier
- Declare classes as abstract
- More unified preload file changes
- Start conversion of kernel classes to namespaces
- A few module updates for recent namespace changes
- A few fixes for issues found in testing of recent changes
- Convert userconfigs to module from extension
- Add caller info to deprecated message
- Add transaction to add and update. Fix pass by ref error.
- Fix incorrect grouping of some where clauses.
- Move userconfigs from extension to module list
- Fix namespace issues
- Fix an odd expression case involving a null 'IN' clause.
- Add schema synchronize step to module update process
- Fix issues introduced in recent conversion.
- Add Patchwork UTF-8 support
- Update for PHP 5.5 compatibility