ikiwiki: Blog names can't be full unicode

Here is the original report from mailing list:

During creation of the blog in ikiwiki it is impossible to give it the name in Russian. It is possible to have the blog in Russian, but it is impossible to give it the name in Russian, ikiwiki refuses to save such name.

Investigate

• Is the name of blog given during creation is same as the display name of the blog?
• If so, is it a limitation that our interface has set or is it an ikiwiki limitation?
• If it is our limitation can it be safely relaxed to allow full range of unicode characters?