gtester.c: adapted to become a rudimentary test binary launcher.

gtester.c: adapted to become a rudimentary test binary launcher.

* gtester.c: increased read buffer size to match common unix pipe buffer size.
added argument parsing and usage. changed io handling to capture and replicate
stdout. fixed io handlers to be cleaned up when the child process exits (catch
G_IO_ERR | G_IO_HUP). we now use pending/iteration instead of a main loop
structure, to keep running until the child process exits and all io has been
processed. launch the test binaries given on the command line. don't quit when
a child couldn't be launched but --keep-going was specified.

svn path=/trunk/; revision=5895