Added Python 3.6

Also added a line to halt duplicate builds

README.md

@@ -3,7 +3,7 @@ rainmeter-python
 
 Originally created by [jblume](https://github.com/jblume), now maintained by [glitchassassin](https://github.com/glitchassassin)
 
-Plugin for Rainmeter enabling Python 3 scripting
+Plugin for Rainmeter enabling Python 3.4/3.5 scripting
 
 Installation
 ------------

appveyor.yml

@@ -26,8 +26,29 @@ environment:
       ARCH: "x64"
       BUILD_PLATFORM: "x64"
       PYTHON_VERSION: "35-x64"
+    - PYTHON: "C:\\Python36"
+      BUILD_ENV: "Visual Studio 14"
+      BUILD_DIR: "x32"
+      ARCH: "x86"
+      BUILD_PLATFORM: "win32"
+      PYTHON_VERSION: "36"
+    - PYTHON: "C:\\Python36-x64"
+      BUILD_ENV: "Visual Studio 14 Win64"
+      BUILD_DIR: "x64"
+      ARCH: "x64"
+      BUILD_PLATFORM: "x64"
+      PYTHON_VERSION: "36-x64"
 
 install:
+  # If there is a newer build queued for the same PR, cancel this one.
+  # The AppVeyor 'rollout builds' option is supposed to serve the same
+  # purpose but it is problematic because it tends to cancel builds pushed
+  # directly to master instead of just PR builds (or the converse).
+  # credits: JuliaLang developers.
+  - ps: if ($env:APPVEYOR_PULL_REQUEST_NUMBER -and $env:APPVEYOR_BUILD_NUMBER -ne ((Invoke-RestMethod `
+        https://ci.appveyor.com/api/projects/$env:APPVEYOR_ACCOUNT_NAME/$env:APPVEYOR_PROJECT_SLUG/history?recordsNumber=50).builds | `
+        Where-Object pullRequestId -eq $env:APPVEYOR_PULL_REQUEST_NUMBER)[0].buildNumber) { `
+          throw "There are newer queued builds for this pull request, failing early." }
 - cmd: >-
     git submodule update --init --recursive