Intermittent commit to get screen capture.
Updated screens & text for contributing changes; deleted unused graphics and added alternative text to
newer graphics; edited site-wide installation section.
last_saved_metadata no longer calls logout.
Merge pull request #1440 from crobinsonut/dev

last_saved_metadata no longer calls logout.
Merge pull request #1441 from pziegfeld/sept_cleanup

Sept cleanup - removed old images, added alt.text  for graphics, updated screens for contributing code, minor edits.
gui bug fixes
add explicit default precision for WV shaders
handle zmq message after websocket is closed in ZMQStreamServer
add try/except handling to project import handler