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