Cleanup tox configuration

There were issues with dependencies and tox environments under Python 3
so refactored the tox configuration to be more consistent and clearer.

- Moved travis to default to Python 3 for linting and tests.
- Fixed missing mock for cairo in sphinx config.
- Collated the base deps sections to improve readability.
- Added PYTEST_ADDOPTS env to override pytest verbosity in just tox
  tests as this was a common option being used.
- Renamed env 'testcoverage' to the more concise 'coverage' and moved
  html creation under single env as handy to have this output as well
  as report.
- Cleaned up the isort config for gtk3.
- Added `bad-continuation` to pylint config as conflcts with black
  formatting.
- Fix isort issue with bbfreeze script. This will likely be removed
  in future so just skip sorting it.

1 files changed, 9 insertions, 7 deletions

diff --git a/.travis.yml b/.travis.yml
index 30da3e24e..0b5f11450 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ sudo: required
 
 language: python
 python:
-  - 2.7
+  - 3.5
 cache: pip
 virtualenv:
   system_site_packages: true
@@ -16,8 +16,8 @@ matrix:
   include:
     - name: Unit tests - Python 2
       env: TOX_ENV=py27
+      python: 2.7
     - name: Unit tests - Python 3
-      python: 3.5
       env: TOX_ENV=py3
     - if: commit_message =~ SECURITY_TEST
       env: TOX_ENV=security
@@ -25,8 +25,9 @@ matrix:
       env: TOX_ENV=lint
     - name: Docs build
       env: TOX_ENV=docs
-    - name: PyGTK unit tests
-      env: TOX_ENV=pygtkui
+      python: 2.7
+    - name: GTK unit tests
+      env: TOX_ENV=gtkui
     - name: Plugins unit tests
       env: TOX_ENV=plugins
 
@@ -46,8 +47,9 @@ addons:
 # Install dependencies
 install:
   - pip install tox tox-venv
-  - "if [ $TOX_ENV == 'pygtkui' ]; then
-    sudo apt install python-gi python-gi-cairo gir1.2-gtk-3.0;
+  - "if [ $TOX_ENV == 'gtkui' ]; then
+    sudo apt install python-gi python-gi-cairo python3-gi python3-gi-cairo \
+    gir1.2-gtk-3.0;
     fi"
   - "if [ $TOX_ENV == 'security' ]; then
     testssl_url=https://github.com/drwetter/testssl.sh/archive/v2.9.5-5.tar.gz;
@@ -59,7 +61,7 @@ before_script:
   - export PYTHONPATH=$PYTHONPATH:$PWD
   - python -c "import libtorrent as lt; print(lt.__version__)"
   # Start xvfb for the GTKUI tests
-  - "if [ $TOX_ENV == 'pygtkui' ]; then
+  - "if [ $TOX_ENV == 'gtkui' ]; then
     /sbin/start-stop-daemon --start --quiet --background \
     --make-pidfile --pidfile /tmp/custom_xvfb_99.pid \
     --exec /usr/bin/Xvfb -- :99 -ac -screen 0 1280x1024x16;