uddeIM 2.1 work in progress

This is the current changelog for uddeIM 2.1.

Don't ask for a release day. It is still in development. People who really need a function could try the trunk version on their own risk (to be honest, it is running on my own sites without any problems for some weeks now).

Following features are new 2.1:
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1.) Added Joo!CM support
2.) Japanese language file added
3.) JIM importer fixed
4.) Attachment plugin: certain files are blocked by default (e.g. php, cgi)
5.) Attachment plugin: allowed extensions can be specified
6.) Public frontend: Option "Email required" added
7.) You can specify a time period a user has to wait until he can send messages
8.) Internal reconstructions regarding system messages and copy2me messages
(performance boost for very large sites, e.g. >100000 members)
9.) uddeIM API does not try to load language files multiple times
10.) Bugfix regarding message linking (warning when PHP >5.0.4 was used)
11.) Managers do not longer have access to uddeIM backend
12.) A few minor bugfixes