Add some checking to the samplers

For the pymultinest and nestle samplers only
- Adds equivalent parameters nlive, n_live_points, npoints etc all do
  the same thing
- Adds checking for any kwargs given to run_sampler that will not be
  used. Removes them and warns the user.

peyote/sampler.py

@@ -100,6 +100,15 @@ class Sampler(object):
     def kwargs(self, kwargs):
         self.__kwargs = kwargs
 
+    def verify_kwargs_against_external_sampler_function(self):
+        args = inspect.getargspec(self.external_sampler_function).args
+        for user_input in self.kwargs.keys():
+            if user_input not in args:
+                logging.warning(
+                    "Supplied argument '{}' not an argument of '{}', removing."
+                    .format(user_input, self.external_sampler_function))
+                self.kwargs.pop(user_input)
+
     def initialise_parameters(self):
 
         for key in self.priors:
@@ -177,13 +186,19 @@ class Nestle(Sampler):
     @kwargs.setter
     def kwargs(self, kwargs):
         self.__kwargs = kwargs
+        if 'npoints' not in self.__kwargs:
+            for equiv in ['nlive', 'nlives', 'n_live_points']:
+                if equiv in self.__kwargs:
+                    self.__kwargs['npoints'] = self.__kwargs.pop(equiv)
 
     def run_sampler(self):
         nestle = self.external_sampler
+        self.external_sampler_function = nestle.sample
         if self.kwargs.get('verbose', True):
             self.kwargs['callback'] = nestle.print_progress
+        self.verify_kwargs_against_external_sampler_function()
 
-        out = nestle.sample(
+        out = self.external_sampler_function(
             loglikelihood=self.log_likelihood,
             prior_transform=self.prior_transform,
             ndim=self.ndim, **self.kwargs)
@@ -231,9 +246,18 @@ class Pymultinest(Sampler):
         if self.__kwargs['outputfiles_basename'].endswith('/') is False:
             self.__kwargs['outputfiles_basename'] = '{}/'.format(
                 self.__kwargs['outputfiles_basename'])
+        if 'n_live_points' not in self.__kwargs:
+            for equiv in ['nlive', 'nlives', 'npoints', 'npoint']:
+                if equiv in self.__kwargs:
+                    self.__kwargs['n_live_points'] = self.__kwargs.pop(equiv)
 
     def run_sampler(self):
         pymultinest = self.external_sampler
+        self.external_sampler_function = pymultinest.run
+        self.verify_kwargs_against_external_sampler_function()
+        # Note: pymultinest.solve adds some extra steps, but underneath
+        # we are calling pymultinest.run - hence why it is used in checking
+        # the arguments.
         out = pymultinest.solve(
             LogLikelihood=self.log_likelihood, Prior=self.prior_transform,
             n_dims=self.ndim, **self.kwargs)