space, and tab, removing digits. Having digits in this list makes a
flag like `T42 generate a parse error. This change makes `17m3s' an
invalid time-spec (you need a space).
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@3932 ec53bebd-3082-4978-b11e-865c3cabbd6b