Add Python 3.7 support

.travis.yml

@@ -36,11 +36,15 @@ matrix:
     - os: linux
       sudo: required
       language: python
-      python: 3.5
+      python: "3.5"
     - os: linux
       sudo: required
       language: python
-      python: 3.6
+      python: "3.6"
+    - os: linux
+      sudo: required
+      language: python
+      python: "3.7-dev"
     - os: osx
       osx_image: xcode8
       language: generic

README.rst

@@ -125,9 +125,7 @@ If you detect an issue, please:
 Requirements
 ------------
 
-Runs on CPython 3.6, and requires external program installations of Ghostscript, Tesseract OCR, QPDF, and Leptonica. ocrmypdf is pure Python, but uses CFFI to portably generate library bindings.
+Runs on CPython 3.5, 3.6 and 3.7. Requires external program installations of Ghostscript, Tesseract OCR, QPDF, and Leptonica. ocrmypdf is pure Python, but uses CFFI to portably generate library bindings.
-
-Python 3.5 is also supported.
 
 Press & Media
 -------------

docs/installation.rst

@@ -168,7 +168,7 @@ Install or upgrade the required Homebrew packages, if any are missing:
     brew install libxml2 libffi leptonica
     brew install unpaper   # optional
 
-Python 3.5 and 3.6 are supported.
+Python 3.5, 3.6 and 3.7 are supported.
 
 Install the required Tesseract OCR engine with the language packs you plan to use:
 

setup.py

@@ -221,6 +221,7 @@ setup(
     classifiers=[
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
         "Development Status :: 5 - Production/Stable",
         "Environment :: Console",
         "Intended Audience :: End Users/Desktop",

src/ocrmypdf/_unicodefun.py

@@ -40,6 +40,11 @@ import codecs
 
 def verify_python3_env():
     """Ensures that the environment is good for unicode on Python 3."""
+
+    # PEP 538 changes in Python 3.7 should make this wrangling unnecessary
+    if sys.version_info[0:3] >= (3, 7, 0):
+        return
+
     try:
         import locale
         fs_enc = codecs.lookup(locale.getpreferredencoding()).name