Graphstream may livelock: fail fast on inconsistent parameters

[DanySK]

Hi,
I noticed that some parameters combination cause graphstream 2.0 to loop. For instance, creating a Lobster with parameters (1, 1) causes the library to loop indefinitely.
Parameter coherence should be checked upfront, and I'd recommend a fail-fast policy, so that clients immediately know when they are doing things incorrectly.