Should be a ~ between shortseries and number

[dcpurton]

The shortseries+number macro probably should be:

\newbibmacro*{shortseries+number}{%
  \usebibmacro{shortseries}%
  \setunit{\addnbspace}%
  \iffieldundef{seriesseries}
    {}
    {\printfield{seriesseries}%
     \setunit*{/}}%
  \printfield{number}%
  \newunit}