Clean up/standardize handling of various output files.

Clean up/standardize handling of various output files.
No more non-intuitive behavior shifts depending on whether
outputDirectory is set (at the expense of backwards compatibility).
outputDirectory is now always valid, defaults to ".".

dev/etherdump.cc:
    Use makeOutputStream() to create output file.
    New behavior: actually complain if dump file can't
    be opened, instead of quietly ignoring the problem.
dev/etherdump.hh:
dev/simconsole.cc:
dev/simconsole.hh:
    Use makeOutputStream() to create output file.
sim/builder.cc:
sim/builder.hh:
sim/main.cc:
    builderStream() is now *configStream.
sim/serialize.cc:
    outputDirectory is now always valid, no need to check.
sim/universe.cc:
    Clean up/standardize handling of various output files.
    No more non-intuitive behavior shifts depending on whether
    outputDirectory is set (at the expense of backwards compatibility).
    outputDirectory is now always valid, defaults to ".".
    New function makeOutputStream() does "the right thing" to
    associate a stream with a filename.

--HG--
extra : convert_revision : a03c58c547221b3906e0d6f55e4a569843f2d646