Remove newly deprecated classes and functions

Classes and functions removed:
- PyMC3Variable
- ObservedRV
- FreeRV
- MultiObservedRV
- TransformedRV
- ArrayOrdering
- VarMap
- DataMap
- _DrawValuesContext
- _DrawValuesContextBlocker
- is_fast_drawable
- _compile_theano_function
- vectorize_theano_function
- get_vectorize_signature
- _draw_value
- draw_values
- generate_samples
- fast_sample_posterior_predictive

Modules removed:
- pymc3.distributions.posterior_predictive
- pymc3.tests.test_random

docs/source/api/distributions/utilities.rst

@@ -12,9 +12,6 @@ Distribution utility classes and functions
   DensityDist
   TensorType
 
-  draw_values
-  generate_samples
-
 
 .. autoclass:: Distribution
 .. autoclass:: Discrete
@@ -23,6 +20,3 @@ Distribution utility classes and functions
 .. autoclass:: DensityDist
     :members:
 .. autofunction:: TensorType
-
-.. autofunction:: draw_values
-.. autofunction:: generate_samples

docs/source/api/variables.rst

@@ -6,22 +6,5 @@ Random Variables
 The normal PyMC3 programmer will typically not need to interact with these classes, except possibly when debugging.  Otherwise they are primarily of interest to developers.
 
 
-.. autoclass:: PyMC3Variable
-    :members:
-
-
 .. autoclass:: ValueGradFunction
     :members:
-
-
-.. autoclass:: FreeRV
-    :members:
-
-.. autoclass:: ObservedRV
-    :members:
-
-.. autoclass:: MultiObservedRV
-    :members:
-
-.. autoclass:: TransformedRV
-    :members: