Update sandbox requirement mechanism.

We seperated base and py35 as a part of the upgrade to python 3 so
that we could get newer versions of some requirements during that
upgrade.  This change is the first step in removing the old requirements
files that were only relevant to python 2.

We leave the python version centric named files instead of base because
we'll need to bump the version of this file regularly and clearly
indicating what version of python it's for makes it easier to reason
about.

requirements/edx-sandbox/base.in

-# Packages to install in the Python sandbox for secured execution of code provided by course authors.
-#
-# DON'T JUST ADD NEW DEPENDENCIES!!!
-#
-# If you open a pull request that adds a new dependency, you should:
-#   * verify that the dependency has a license compatible with AGPLv3
-#   * confirm that it has no system requirements beyond what we already install
-#   * run "make upgrade" to update the detailed requirements files
-
-
-# We pin things specifically in this file beacuse we want to be very explicit about
-# updating dependencies to the sandbox since they can impact how custom response code is run.
-# We can then use constraints.txt to constrain any sub-dependencies that may need to be held back.
-
-
--c ../constraints.txt
-
--r shared.txt                       # Dependencies in common with LMS and Studio
-chem                                # A helper library for chemistry calculations
-matplotlib==2.2.4                   # 2D plotting library
-numpy==1.16.5                       # Numeric array processing utilities; used by scipy
-pyparsing==2.2.0                    # Python Parsing module
-random2==1.0.1                      # Implementation of random module that works identically under Python 2 and 3
-scipy==1.2.1                        # Math, science, and engineering library
-sympy==1.4                          # Symbolic math library
-git+https://github.com/edx/openedx-calc.git@e9b698c85ad1152002bc0868f475f153dce88952#egg=calc==0.4
-
-# Install these packages from the edx-platform working tree
-# NOTE: if you change code in these packages, you MUST change the version
-# number in its setup.py or the code WILL NOT be installed during deploy.
--e common/lib/sandbox-packages
--e common/lib/symmath

requirements/edx-sandbox/base.txt

-#
-# This file has been frozen for the benefit of Python 2.7 sandboxes, and
-# "make upgrade" no longer updates it.  It can be removed once that
-# version of the sandbox is no longer run in production.  Before removal,
-# the configuration repository needs to be updated to use the new file:
-# https://github.com/edx/configuration/blob/master/playbooks/roles/edxapp/defaults/main.yml#L1628
-# Also, this change needs to be announced and communicated to partners
-# before implementation.
-#
-common/lib/sandbox-packages
-common/lib/symmath
-backports.functools-lru-cache==1.6.1  # via matplotlib
-git+https://github.com/edx/openedx-calc.git@e9b698c85ad1152002bc0868f475f153dce88952#egg=calc==0.4
-cffi==1.13.2
-git+https://github.com/edx/openedx-chem.git@ff4e3a03d3c7610e47a9af08eb648d8aabe2eb18#egg=chem==1.0.0
-cryptography==2.8
-cycler==0.10.0            # via matplotlib
-ipaddress==1.0.23
-kiwisolver==1.1.0         # via matplotlib
-lxml==3.8.0
-markupsafe==1.1.1
-matplotlib==2.2.4
-networkx==1.7
-nltk==3.4.5
-numpy==1.7.2
-pycparser==2.19
-pyparsing==2.2.0
-python-dateutil==2.8.1    # via matplotlib
-pytz==2019.3              # via matplotlib
-random2==1.0.1
-scipy==0.14.0
-singledispatch==3.4.0.3
-six==1.13.0
-subprocess32==3.5.4       # via matplotlib
-sympy==0.7.1
-
-# The following packages are considered to be unsafe in a requirements file:
-# setuptools

requirements/edx-sandbox/py35.in

@@ -15,15 +15,15 @@
 -c ../constraints.txt
 
 -r shared.txt                       # Dependencies in common with LMS and Studio
-chem
+chem                                # A helper library for chemistry calculations
 matplotlib==2.2.4                   # 2D plotting library
 networkx==2.2                       # Utilities for creating, manipulating, and studying network graphs
 numpy==1.16.5                       # Numeric array processing utilities; used by scipy
-openedx-calc
+openedx-calc<2.0.0
 pyparsing==2.2.0                    # Python Parsing module
 random2                             # Implementation of random module that works identically under Python 2 and 3
 scipy==1.2.1                        # Math, science, and engineering library
-sympy==1.6.2                         # Symbolic math library
+sympy==1.6.2                        # Symbolic math library
 
 # Install these packages from the edx-platform working tree
 # NOTE: if you change code in these packages, you MUST change the version