Update of LabelTensor class and fix Simplex domain (#362)

*Implement new methods in LabelTensor and fix operators

pina/problem/abstract_problem.py

@@ -36,7 +36,15 @@ class AbstractProblem(metaclass=ABCMeta):
 
     @property
     def input_pts(self):
-        return self.collector.data_collections
+        to_return = {}
+        for k, v in self.collector.data_collections.items():
+            if 'input_points' in v.keys():
+                to_return[k] = v['input_points']
+        return to_return
+
+    @property
+    def _have_sampled_points(self):
+        return self.collector.is_conditions_ready
     
     def __deepcopy__(self, memo):
         """
@@ -165,3 +173,6 @@ class AbstractProblem(metaclass=ABCMeta):
 
         # store data
         self.collector.store_sample_domains(n, mode, variables, locations)
+
+    def add_points(self, new_points_dict):
+        self.collector.add_points(new_points_dict)