Update GitHub issue/PR templates

Add a default, basic PR template. Also move from legacy singular issue
template to the newer, "select an option" issue template style on
GitHub.

.github/ISSUE_TEMPLATE.md → .github/ISSUE_TEMPLATE/bug_report.md

@@ -1,9 +1,8 @@
-### For feature requests
-
-Include a clear description and an example or even a scholarly source of information about how the calculation, plot, etc. works
-
-### For bugs
-
+---
+name: Bug Report
+about: Let us know that something isn't working properly
+labels: "Type: Bug"
+---
 Try to include: 
 - Code Sample, a copy-pastable example if possible
 - A ["Minimal, Complete and Verifiable Example"](http://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) will make it much easier for maintainers to help you
@@ -14,6 +13,7 @@ Try to include:
 ```
 - Problem description: this should explain **why** the current behavior is a problem and why the expected output is a better solution.
 - Expected output
+- Which platform (Linux, Windows, Mac, etc.)
 - Versions. Include the output of:
   * `python --version`
   * `python -c 'import metpy; print(metpy.__version__)'

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,6 @@
+---
+name: Feature Request
+about: Suggest an idea for something new to add
+labels: "Type: Feature"
+---
+Include a clear description and an example or even a scholarly source of information about how the calculation, plot, etc. works

.github/pull_request_template.md

@@ -0,0 +1,18 @@
+<!--
+Thanks for contributing a pull request! Please ensure you have taken a look at
+the contribution guidelines: https://github.com/Unidata/MetPy/blob/master/CONTRIBUTING.md
+-->
+
+#### Description Of Changes
+
+#### Checklist
+<!--
+Feel free to remove check-list items aren't relevant to your change
+
+Please use keywords (e.g., Fixes, Closes) to create link to the issues or pull
+requests you resolved, so that they will automatically be closed when your pull
+request is merged. See https://github.com/blog/1506-closing-issues-via-pull-requests
+-->
+- [ ] Closes #xxxx
+- [ ] Tests added
+- [ ] Fully documented