Improve bin graph dumping, by using the envvar to specify a path.

Original commit message from CVS:
* docs/gst/running.xml:
* gst/gst.c:
* gst/gstdebugutils.c:
* gst/gstdebugutils.h:
* tools/gst-launch.c:
Improve bin graph dumping, by using the envvar to specify a path.
Rename the envvar to GST_DEBUG_DUMP_DOT_DIR.
6 files changed