Adding multiple models to a config causes errors due to duplicated clock parameters in the statespace

[lmaurits]

When multiple [model] sections with different names are present in a config file, the clockRate parameter and associated things (priors, operators, etc.) are placed into the XML file twice, causing BEAST to error out.

The ideal solution to this has the user being able to easily choose between a single clock shared across all models, or independent clocks for each model.

[lmaurits]

Fixed in 80526b0.