* Fix a constant define.
? Modify merge system's internal functions to fix Chinese UTF-8 converting problem.

…rt_ucusers](https://github.com/yuliu/mybb-merge-system/wiki/import_ucusers)

+ Add `class_dependencies` field in main Board converter file.
* Modified `index.php` to allow customed `import_` modules derived from MyBB Merge System's internal base abstract classes in `./merge/resources/modules`.
* Modified `class_converter.php` to allow different database connections.
* Modified `functions.php` to allow encoding setting when using the customized `dz_my_strtolower` function.

…g in mb* function to support whole charset of `gbk`.

+ Add `users` module.
+ Add useful default values for Discuz! import_ucuser module.
* Remove any non-system usergroups in default usergroup mapping.
* Fix duplicated user checking in Discuz! import_ucuser module, since UCenter's email field length is less than Discuz!'s.
* Fix duplicated user data merging.
* Always use the same mb_strtolower() or strtolower() to avoid UTF-8 converting issues.
* Remove UCenter import_uid define marco since it's useless.
* Fix import module dependencies checking mechanism.
* Minor changes.

* Fix custom module dependency problem.

* Change `userfields` dependency to none.

* Add `usergroups` to `forumperms` dependencies to rely on usergroup's default permissions.

+ Add threadprefixes cache support for future import features like threads.
* Minor changes.

* Revert a change in `userfields`. All modules needs review, because I got the knowledge that MySQL returns results as string in any column in PHP.

+ Add `threads` module.
* Revert a change in `userfields`. All modules needs review, because I got the knowledge that MySQL returns results as string in any column in PHP.

* Make `dz_unserialize()` a member function of Discuz! converter.

* Move some common functions into converter's class.
* Fix moved thread information.

* Minor changes.
? Code should be reviewed and some functions added in `./resources/functions.php` may be moved to the converter's class.

…sted [size], [color], etc., are not well handled. HTML output needs fix on tags without a closing tag.

+ Add a cleanup() function in `posts` module to clean any thread that has no post in it.
* Fix moved thread importing issue.

* Fix several parser issues.
* Minor changes.

* Fix bugs. Still so many bugs there.

… to MyBB only support font name with very basic ASCII characters.

…font handler.

…month` folder under MyBB's upload path.

? Mime type recognition in older version of PHPs are problematic, so the importer use a mime types table from Apache HTTPd.

+ Add UCenter/Discuz! user login in `loginconvert.php`.
* Separate UCenter importer from Discuz! X2.5 importer.
* Revert changes in `./resources/functions.php` and `./resources/class_converter.php`. Customized functions now reside in the converter's class.

…rred file is not a valid image file, since it's limited by PHP GD that is the default used by MyBB. However, the file of original width and height is still saved.

…y if it's not been set, to avoid double headers appear.

* Still in the `cleanup()` of the `posts` module, fix the the internal progress indicator to make `rebuild_thread_counters()` working correctly.

+ Add a constant of switching `users`'s dependency on `settings`.
* Minor changes.

* Changes in `README.md` in Discuz! X2.5 and Discuz! UCenter converters.

* Change redirect files to be generated in a folder under MyBB's upload path.

…dules in Discuz! X2.5. All available redirects should be generating correctly now.

? Major coding of Discuz! X2.5 and UCenter converters is near its completion, code tidy and clean up is following up.

…users` module.

Merge from mybb/merge-system:feature

Pull from upstream.

Fix typos.

In `posts` module of `dxz25`, if a post content is empty, use subject of this post instead.
Code cleanup.

Rewrite README.me for `dzx25`.