keytests: Allow for checking multiple log files

keytests: Allow for checking multiple log files

Handle name may be arbitrary string mathing '[A-Za-z0-9]*'.
This is then used by appending to the commands for the control file.
For instance select 'Alpha' as handle for the control file 'abc'
'COAlpha: abc' ==> open 'abc' for write
'CCAlpha:' ==> close 'abc'