intermediate ps file overwrites existing one

[Martin Tarenskeen]

bugreport / change request

%%% tiny example "example.ly": %%%

\version "2.19.19"
{c' d' e' f'}

%%% commandline actions --> result %%%
$ lilypond --ps example.ly --> creates example.ps, which I want to keep
$ lilypond example.ly --> creates example.pdf, without telling me it
                      --> brutally overwrites and then deletes example.ps

%%% change request: %%%
Maybe lilyPond should create a unique temporary filename using something 
like mktemp to create the intermediate files.

P.S. As a side-effect this would also solve a funny issue that's happening 
on systems when using a filename like "lines.ly". The intermediate 
filename "lines.ps" confuses Ghostscript, as there is also a "lines.ps" 
file in the Ghostscript library path.

--

MT