restrictions on experiments with MLR mbo

[alinaciuysal]

User should not be able to do following at the same time:

• provide 3-4 changeable variables with default or larger intervals (e.g. 2 to 12)
• select mlr mbo strategy with very small number of iterations and random starts

if these are observed, then mlr mbo gives an error related with "experiment space", thus resulting in an error state.

to be discussed with Ilias & Janek

[alinaciuysal]

implemented here