Resolve "Introduce conditional prior sets"

Closes #270 (closed)

PP test show that the new capabilities do not interfere with the results we are getting so far. This test is done without any conditional priors, it just shows that everything still works as expected.

https://ldas-jobs.ligo.caltech.edu/~moritz.huebner/conditional_prior_pp/outdir_pp_test_4s/pp.png

bilby/core/sampler/base_sampler.py

@@ -276,7 +276,7 @@ class Sampler(object):
         self._check_if_priors_can_be_sampled()
         if isinstance(self.priors, ConditionalPriorDict):
             theta = self.priors.sample()
-            theta = theta.values()
+            theta = list(theta.values())
         else:
             theta = [self.priors[key].sample()
                      for key in self._search_parameter_keys]
@@ -302,7 +302,7 @@ class Sampler(object):
         for _ in range(n_evaluations):
             if isinstance(self.priors, ConditionalPriorDict):
                 theta = self.priors.sample()
-                theta = theta.values()
+                theta = list(theta.values())
             else:
                 theta = [self.priors[key].sample()
                          for key in self._search_parameter_keys]