gnetlist: fix whitespaces in source code of all the backends

Tabs have been replaced with spaces.
Trailing whitespaces have been removed.
Tabs in the "display" procedure strings have been replaced with "\t".
gnetlist: consistent naming of output files
gnetlist: add support of output to stdout for most of backends

The "-o" switch can now be used with "-" for almost all the gnetlist backends
(excluding yet allegro, gsch2pcb, osmond, spice-sdb, and vams  for various
reasons) to output data directly to stdout instead of a file.
Some messages in gnetlist.c & gnetlist.scm were redirected to stderr in order
to not mingle them with netlist data when stdout is redirected to other files
or pipes.

Affects-bug: lp-700287
gnetlist: support of the '-o -' option for the osmond backend

Affects-bug: lp-700287
gnetlist: added support of output to stdout for spice-sdb

Additionally, in order not to mix spice-sdb netlist output with user
messages, the (message ...) procedure was added.

Affects-bug: lp-700287
gnetlist: redirected some gnetlist messages to stderr

Before now, all backends used file ports explicitly and their output
did not mix with possible gnetlist error messages that went to stdout.
Now, as many of the backends may output their data to stdout, those
error messages may mix with the output of the backends, which may lead
to failing of some tests. So, the messages have been redirected to not
affect stdout.

Affects-bug: lp-700287
gnetlist: support of output to stdout for the gsch2pcb backend

Affects-bug: lp-700287
gnetlist: support for output to stdout for the allegro backend

Affects-bug: lp-700287
gnetlist: deleted comment

I've tried the code mentioned and it works quite well now. There is no
sense to keep it here any more.
gnetlist: support of output to stdout for the vams backend

Affects-bug: lp-700287
gnetlist: add tests for output of data to stdout

Closes-bug: lp-700287
gnetlist: update man page and NEWS
gnetlist: use standard 'dirname' procedure

Old code having the same functionality as 'dirname' has been
replaced with that procedure.
gnetlist: simplified the bae backend

Explicit using of an output port in procedures has been eliminated.
Instead, (set-current-output-port) is used now.
gnetlist: removed useless procedures in the bae backend
gnetlist: simplified code of the bom and bom2 backends

Port is not specified explicitly in 'display' procedures now.
Error output is redirected to stderr to prevent mixing it with backend
output when output to stdout is used.
gnetlist: simplified the calay backend

Using of (set-current-output-port ...) instead of explicit port
specifying.
gnetlist: simplified source code of the PCB backend
gnetlist: simplified the cascade backend source code
gnetlist: simplified the drc2 backend source code