ISSUE_TEMPLATE: Use the newer issue templates

This utilizes the newer Github issue templates. They allow for the user
to specify what type of issue they are submitting to allow for a more
specific issue template to be shown.

In addition to a hopefully easier to read/parse/follow bug report
template, this also include templates for enhancements and i3
compatibility. This also includes a link to the IRC under the section
title Questions.

For the three templates, the labels bug, enhancement, and i3-compat will
be automatically applied for the appropriate report to assist in
triaging.

Hopefully, this will result in less questions and issues for new window
management functionality on Github and allow for better quality issues
being submitted. At the very least, it allows us to outline our
stances for bugs, enhancements, and i3-compatibility in an easier to
read format.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Questions
+    url: "http://webchat.freenode.net/?channels=sway&uio=d4"
+    about: "Please ask questions on IRC in #sway on irc.freenode.net"