github: Migrate template to the new format, implement new ones

This commit migrates the old issue template to the new format
documented on the following page:

https://help.github.com/en/github/building-a-strong-community/about-issue-and-pull-request-templates

The old "issue template" is now a generic "bug report".

New templates have also been added:

* crash report
* feature request
* question

Providing users with those templates allows reducing redundant
questions to the reporter ("where is the stacktrace", "what is the
usecase" etc), and assigning labels to the created issues
automatically.

A pull request template that refers to the CONTRIBUTING document and
reminds the reporter to create a waiver commit is also implemented
by this commit.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,11 @@
+---
+name: Bug report
+about: Report an unexpected behaviour with the editor
+labels: bug
+---
+
+### Steps <!-- how to reproduce the issue? -->
+
+### Outcome <!-- what is the result of the above steps? -->
+
+### Expected <!-- what should have been the result of the above steps? -->

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1 @@
+blank_issues_enabled: true

.github/ISSUE_TEMPLATE/crash_report.md

@@ -0,0 +1,15 @@
+---
+name: Crash report
+about: Report a crash of the editor while in-use
+labels: bug, crash
+---
+
+<!--
+If you have a reproducer for the crash you've experienced, please make sure
+to include a demangled stacktrace (i.e. pass it to `c++filt`) produced
+by an instance of the editor built in debug mode (`make debug=yes`).
+-->
+
+### Steps <!-- what steps allow reproducing the crash? -->
+
+### Outcome/Stacktrace <!-- what is the outcome of the above steps? is there any stacktrace? -->

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,17 @@
+---
+name: Feature request
+about: Ask for a feature to be implemented and included in the next release
+labels: feature request
+---
+
+<!--
+Please make sure that no request has already been made for your feature
+by checking the issue tracker (tag: `feature request`). If it was to be the
+case, feel free to post a reply in the already existing issue, indicating
+that you're interested (and possibly the use you would make for the feature,
+if not already mentioned).
+-->
+
+### Feature <!-- what do you want implemented that is not already available in the development version? -->
+
+### Usecase <!-- what use do you have for the feature, if it's not self-evident (e.g. a hook, option)? -->

.github/ISSUE_TEMPLATE/question.md

@@ -0,0 +1,13 @@
+---
+name: Question
+about: Couldn't find an answer in the documentation? Ask away!
+labels: question
+---
+
+<!--
+Please make sure that you check the onboard documentation (`:doc …`),
+the community wiki (hosted on Github) and other issues before creating an
+issue for your question.
+
+You can also drop by our IRC channel to get instant (hopefully) feedback.
+-->

.github/PULL_REQUEST_TEMPLATE/pull_request_template.md

@@ -0,0 +1,7 @@
+<!--
+If this is your first contribution to the Kakoune project, make sure to
+include an empty "waiver" commit to your Pull Request, as described in the
+following document:
+
+https://github.com/mawww/kakoune/blob/master/CONTRIBUTING
+-->

.github/issue_template.md

@@ -1,10 +0,0 @@
-<!--
-If you're not reporting a bug (e.g. requesting a feature or asking a general question), feel free to remove this template.
-Otherwise, please edit the following sections with the relevant information ().
--->
-
-### Steps <!-- how to reproduce the issue? -->
-
-### Outcome <!-- what is the result of the above steps? -->
-
-### Expected <!-- what should have been the result of the above steps? -->