Add msgid to warnings, so that they can be turned off by the calling program.

I did this so that the TestAllExampleScenes script could supress the warning.  I didn't think it looked good for a warning to print out during a test.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>
Supress warnings about output scaling

Didn't want the test program to throw warnings.

Also added calls to jheapcl if it is present on path, to try to minimize jave heap problems.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>