Allow default prefixes and aliases with spaces

[Vampire]

Allow default prefixes and aliases with spaces, so that you can e. g. make t as the prefix for a translation bot and so on. Currently spaces in prefix or alias are simply removed by sdcf4j.

[Vampire]

A maybe better alternative might be to only support a trailing space for the default prefix and add a prefix field for the command that has the same possibility. Then for the concrete command only non-space is allowed (throwing an exception, not silently removing the spaces), but sub-(sub-(sub-))commands then should be added.