turns all whitespace into underscores, shows leading
sigil if the alias is non-empty, so the user doesn't get
confused about whether they have to input a # or not.
Change-Id: Ic81e69cc3f0074d63a67b976c9bda32f8de025de
Tries its best to not allow aliases that are too
long (full alias including leading #, : in the
middle, and homeserver domain name must not exceed
255 bytes.
Change-Id: I1e784a94cb599eca7e30736d666b20e37aad5444
A choice of public or private is offered, which maps to matrix'
visibility parameter. A name can also be provided.
Change-Id: I34d99acbc4624a9ed54ca6f6609573d5fc1049da
