Allow configuring tracing directory through environment variables
Closes #105 (closed)
Uses the following logic:
- Use $ROS_TRACE_DIR if ROS_TRACE_DIR is set and not empty.
- Otherwise, use $ROS_HOME/tracing, using ~/.ros for ROS_HOME if not set or if empty.
See also a similar logic for the logging directory in:
Edited by Christophe Bédard