Test Python 3.8 on Travis
diff --git a/.travis.yml b/.travis.yml
index 0c8efe3..d40304f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -204,6 +204,11 @@
       dist: xenial
     - compiler: gcc
       os: linux
+      env: SWIGLANG=python PY3=3 VER=3.8
+      sudo: required
+      dist: xenial
+    - compiler: gcc
+      os: linux
       env: SWIGLANG=python SWIG_FEATURES=-builtin
       sudo: required
       dist: xenial
@@ -217,7 +222,7 @@
       sudo: required
       dist: xenial
     - os: linux
-      env: SWIGLANG=python SWIG_FEATURES=-builtin GCC=6 CPP11=1 PY3=3 VER=3.7
+      env: SWIGLANG=python SWIG_FEATURES=-builtin GCC=6 CPP11=1 PY3=3 VER=3.8
       sudo: required
       dist: xenial
     - compiler: gcc
@@ -237,12 +242,17 @@
       dist: xenial
     - compiler: gcc
       os: linux
-      env: SWIGLANG=python SWIG_FEATURES="-builtin -O" PY3=3 VER=3.7
+      env: SWIGLANG=python SWIG_FEATURES=-builtin PY3=3 VER=3.8
       sudo: required
       dist: xenial
     - compiler: gcc
       os: linux
-      env: SWIGLANG=python SWIG_FEATURES=-builtin PY3=3 VER=3.7 SWIGOPTPY3=
+      env: SWIGLANG=python SWIG_FEATURES="-builtin -O" PY3=3 VER=3.8
+      sudo: required
+      dist: xenial
+    - compiler: gcc
+      os: linux
+      env: SWIGLANG=python SWIG_FEATURES=-builtin PY3=3 VER=3.8 SWIGOPTPY3=
       sudo: required
       dist: xenial
     - compiler: gcc
@@ -252,7 +262,7 @@
       dist: xenial
     - compiler: gcc
       os: linux
-      env: SWIGLANG=python SWIG_FEATURES=-O PY3=3 VER=3.7
+      env: SWIGLANG=python SWIG_FEATURES=-O PY3=3 VER=3.8
       sudo: required
       dist: xenial
     - compiler: gcc
@@ -384,7 +394,7 @@
       sudo: required
       dist: xenial
     - os: linux
-      env: SWIGLANG=python GCC=8 CPP17=1 PY3=3 VER=3.7
+      env: SWIGLANG=python GCC=8 CPP17=1 PY3=3 VER=3.8
       sudo: required
       dist: xenial
     - os: linux
@@ -396,7 +406,7 @@
       sudo: required
       dist: xenial
     - os: linux
-      env: SWIGLANG=python GCC=9 CPP17=1 PY3=3 VER=3.7
+      env: SWIGLANG=python GCC=9 CPP17=1 PY3=3 VER=3.8
       sudo: required
       dist: xenial
     - compiler: gcc