Some spaces where wrongly placed, especially if one of the variables
doesn't exist (e.g. `rvm_ruby`) where that would add two spaces instead
of one.
Added the red dot (instead of the default `*`) if the branch is dirty.
The bira theme only supported git, now it supports mercurial as well. It
needed ito call `hg_prompt_info` and the `ZSH_THEME_HG_PROMPT_`
variables.
The whitespace in line 13 creates a double whitespace when combined with line 24. Therefore 2 whitespaces appear between ${user_host} and ${current_dir}.
