NetLogo data-export: correct data-ready? handling

data-export:data-ready? is only true after make-model-data
completes

Any other access to the data-export functions sets
data-export:data-ready? to false.
NetLogo data-export: add module-available global

A JavaScript program can check whether the data-export
module is available in a NetLogo applet by checking
for the existence and state of the global variable:

  data-export:module-available
fix AirBags 24.2P, there is no setup-run function
VISUAL AirBags updates