Add RDDL Domains

Repository of problems: https://github.com/AI-Planning/rddl-domains

Notes on what's there:

* Brief domain descriptions should be in the comments header at the top of the _mdp and _pomdp domain files (i.e., not the numbered instance files).

* For the competition:
- **IPPC 2011:** Game of Life, SysAdmin, Navigation, Crossing Traffic, Traffic, Skill Teaching, Elevators, Recon
- **IPPC 2014:** Tamarisk, Wildfire, and Triange Tireworld (+ reuse of Navigation, Crossing Traffic, Traffic, Skill Teaching, Elevators from IPPC 2011)
- **IPPC 2018**