WIP: Install dependencies via pip to support Python 3.9

Reason: Python 3.9 breaks handling of namespace packages:

zc.builout is installed via pip
zc.lockfile is installed via buildout --> zc.lockfile cannot be imported

tox.ini

@@ -1,6 +1,7 @@
 [tox]
 envlist =
     py35,
+    py35-deps,
     py36,
     py37,
     py38,
@@ -10,17 +11,42 @@ envlist =
 [testenv]
 coverage_run = {env:WIN_COV:coverage run}
 commands =
-    {envbindir}/buildout -c {toxinidir}/buildout.cfg buildout:directory={envdir} buildout:develop={toxinidir} install test alltests
-    {[testenv]coverage_run} {envdir}/bin/alltests {posargs:-vc}
-skip_install = true
+    {[testenv]coverage_run} -m zope.testrunner \
+     --test-path=src \
+     {posargs:-vc}
 deps =
     -cconstraints.txt
     coverage
-    setuptools>=36.2
-    zc.buildout>=2.12
+    zope.testrunner
 setenv =
     COVERAGE_FILE=.coverage.{envname}
 
+[testenv:py35-deps]
+commands =
+    {[testenv]coverage_run} -m zope.testrunner \
+     --test-path={envsitepackagesdir} \
+     -s AccessControl \
+     -s Acquisition  \
+     -s DateTime  \
+     -s DocumentTemplate  \
+     -s ExtensionClass  \
+     -s MultiMapping  \
+     -s Persistence  \
+     -s zExceptions  \
+     -s five.localsitemanager \
+     -s Missing \
+     -s Products.BTreeFolder2 \
+     -s Products.ZCatalog \
+     -s Record \
+     {posargs:-vc}
+deps =
+    {[testenv]deps}
+    five.localsitemanager
+    Missing
+    Products.BTreeFolder2
+    Products.ZCatalog
+    Record
+
 [testenv:coverage-report]
 basepython = python3.6
 deps =

versions.cfg

@@ -14,7 +14,7 @@ alabaster = 0.7.12
 appdirs = 1.4.3
 attrs = 19.3.0
 backports.functools-lru-cache = 1.6.1
-beautifulsoup4 = 4.8.1
+beautifulsoup4 = 4.8.2
 bleach = 3.1.0
 buildout.wheel = 0.2.0
 certifi = 2019.11.28