Add GitHub PR and issue templates (#76)

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,23 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+
+---
+
+### Is your feature request related to a problem? Please describe.
+
+A clear and concise description of what the problem is. Ex. I'm always
+frustrated when [...]
+
+### Describe the solution you'd like
+
+A clear and concise description of what you want to happen.
+
+### Describe alternatives you've considered
+
+A clear and concise description of any alternative solutions or features you've
+considered.
+
+### Additional context
+
+Add any other context or screenshots about the feature request here.