`common.sim.legend` issues

[helen-zhu]

• The option quantiles in include.legends is not used
• param_decile in cont.params.to.include can't be used
• Need support for multimodal peak analysis

[helen-zhu]

Possibly also useful to match names between cont.params.to.incude and simulation.params if this is going to be an exported function

[helen-zhu]

Option to specify distributions might also be nice!