Python 3.7 (#20)

* try 3.7

* only master

* try mac

* see

.travis.yml

@@ -5,6 +5,9 @@ python:
 - '3.5'
 - '3.6'
 - 'pypy3'
+branches:
+  only:
+    - master
 env:
   global:
   - LD_LIBRARY_PATH=./libsecp256k1_ext/.libs
@@ -18,6 +21,9 @@ cache:
   - $HOME/.cache/python-dl
 matrix:
   include:
+  - python: 3.7
+    dist: xenial
+    sudo: true
   - os: osx
     language: generic
     osx_image: xcode9
@@ -37,6 +43,12 @@ matrix:
     env:
     - NEED_SSL_FIX=true
     - TRAVIS_PYTHON_VERSION=3.6
+  - os: osx
+    language: generic
+    osx_image: xcode9
+    python: 3.7
+    env:
+    - TRAVIS_PYTHON_VERSION=3.7
   - os: linux
     language: python
     python: 3.5

.travis/build-linux-wheels.sh

@@ -11,7 +11,7 @@ wget -q https://ftp.gnu.org/gnu/gmp/gmp-6.1.2.tar.bz2 && tar -xjpf gmp-*.tar.bz2
 
 # Compile wheels
 for PYBIN in /opt/python/*/bin; do
-	if [[ ${PYBIN} =~ (cp27|cp35|cp36) ]]; then
+	if [[ ${PYBIN} =~ (cp27|cp35|cp36|cp37) ]]; then
 	${PYBIN}/pip wheel /io/ -w wheelhouse/
     fi
 done

.travis/install.sh

@@ -11,6 +11,7 @@ if [[ $TRAVIS_OS_NAME == "osx" ]]; then
 	# going to be as widely compatible as possible
 	PYTHON_PKG_27="https://www.python.org/ftp/python/2.7.15/python-2.7.15-macosx10.6.pkg"
 	PYTHON_PKG_36="https://www.python.org/ftp/python/3.6.5/python-3.6.5-macosx10.6.pkg"
+	PYTHON_PKG_37="https://www.python.org/ftp/python/3.7.0/python-3.7.0-macosx10.6.pkg"
 	GET_PIP="https://bootstrap.pypa.io/get-pip.py"
 
 	# update brew
@@ -55,7 +56,7 @@ if [[ $TRAVIS_OS_NAME == "osx" ]]; then
 			python=/Library/Frameworks/Python.framework/Versions/${TRAVIS_PYTHON_VERSION}/bin/python
 			virtualenv=virtualenv
 			;;
-		3.6)
+		3.6|3.7)
 			python=/Library/Frameworks/Python.framework/Versions/${TRAVIS_PYTHON_VERSION}/bin/python3
 			virtualenv=venv
 			;;