Handle Terminal States

[MaximeBouton]

The conversion from the POMDPs.jl model to the xml file is not using isterminal. Terminal states are assumed to be absorbing state (probability of one to stay in that state).
options:

• Have a warning that tells the user that the transition at the terminal state should be absorbing
• Create a dummy state based on isterminal

[zsunberg]

There also might be a way to have terminal states in the pomdpx format

[MaximeBouton]

I think I already looked a long time ago, it does not seem like there is an explicit placeholder for it:
http://bigbird.comp.nus.edu.sg/pmwiki/farm/appl/index.php?n=Main.PomdpXDocumentation

[zsunberg]

I think I fixed this, but there are no tests for it yet in this package (I tested in with SARSOP though)