Marlin v2.1.2.1 (#154)

* Update Readme to show Marlin v2.1.2.1

Updated for latest 2.1.x version of Marlin

* Update Marlin Sources to v2.1.2.1

Sync with upstream Marlin repo 2.0.x

* Add .github folder for repo enhancements

Adds the following:

- Issue Templates for Bug Report and Feature Request to simplify issues going forward.
- Pull Request Template to simplify changes going forward.
- GitHub Workflow for building all versions of the firmware to simplify releases / testing (also builds on each pull request submitted.)

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -0,0 +1,84 @@
+name: "🐛 Bug Report"
+description: Create a new issue for a bug.
+title: "🐛 [BUG] - <title>"
+labels: [
+  "bug"
+]
+body:
+  - type: textarea
+    id: description
+    attributes:
+      label: "Description"
+      description: Please enter an explicit description of your issue
+      placeholder: Short and explicit description of your incident...
+    validations:
+      required: true
+  - type: textarea
+    id: reprod
+    attributes:
+      label: "Reproduction steps"
+      description: Please provide steps to reproduce the issue reported
+      placeholder: |
+        1. Go to '...'
+        2. Click on '....'
+        3. Scroll down to '....'
+        4. See error
+      render: bash
+    validations:
+      required: true
+  - type: textarea
+    id: screenshot
+    attributes:
+      label: "Screenshots"
+      description: If applicable, add screenshots to help explain your problem.
+      placeholder: |
+        ![DESCRIPTION](LINK.png)
+      render: bash
+    validations:
+      required: false
+  - type: textarea
+    id: logs
+    attributes:
+      label: "Logs"
+      description: Please copy and paste any relevant log output. This will be automatically formatted into code, so no need for backticks.
+      render: bash
+    validations:
+      required: false
+  - type: dropdown
+    id: printers
+    attributes:
+      label: "Printer"
+      description: What printer are you experiencing the issue with?
+      multiple: true
+      options:
+        - FlashForge Dreamer
+        - FlashForge DreamerNX
+        - FlashForge Inventor
+        - Dremel 3D20
+        - Powerspec Ultra 3D
+        - Monoprice Inventor 1
+    validations:
+      required: true
+  - type: textarea
+    id: fwversion
+    attributes:
+      label: "Marlin Version"
+      description: What version of Marlin Firmware are you experiencing the issue with?
+      placeholder: ex. 2.1.2, v0.15.1, etc.
+    validations:
+      required: true
+
+  - type: dropdown
+    id: fwfeatures
+    attributes:
+      label: "Marlin Features"
+      description: What features are enabled for the build you are experiencing the issue with? (if any)
+      multiple: true
+      options:
+        - swap
+        - dir
+        - la
+        - mks
+        - classic
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/config.yml

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

.github/ISSUE_TEMPLATE/feature-request.yml

@@ -0,0 +1,31 @@
+name: "💡 Feature Request"
+description: Create a new issue for a feature request
+title: "💡 [REQUEST] - <title>"
+labels: [
+  "enhancement"
+]
+body:
+  - type: textarea
+    id: reference_issues
+    attributes:
+      label: "Reference Issues"
+      description: Issues that relate to your request (if any)
+      placeholder: "#Issues IDs"
+    validations:
+      required: false
+  - type: textarea
+    id: summary
+    attributes:
+      label: "Summary"
+      description: Provide a brief explanation of the requested feature
+      placeholder: Describe in a few lines your feature request
+    validations:
+      required: true
+  - type: textarea
+    id: basic_example
+    attributes:
+      label: "Basic Example"
+      description: Indicate here some basic examples of your feature.
+      placeholder: A few specific words about your feature request.
+    validations:
+      required: true

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,38 @@
+## What type of PR is this? (check all applicable)
+
+- [ ] Refactor
+- [ ] Feature
+- [ ] Bug Fix
+- [ ] Optimization
+- [ ] Documentation Update
+
+## Description
+
+## Related Tickets & Documents
+
+<!--
+For pull requests that relate or close an issue, please include them
+below.  We like to follow [Github's guidance on linking issues to pull requests](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue).
+
+For example having the text: "closes #1234" would connect the current pull
+request to issue 1234.  And when we merge the pull request, Github will
+automatically close the issue.
+-->
+
+- Related Issue #
+- Closes #
+
+## QA Instructions, Screenshots, Recordings
+
+_Please replace this line with instructions on how to test your changes, a note
+on the devices and browsers this has been tested on, as well as any relevant
+images for UI changes._
+
+## Added/updated tests?
+
+- [ ] Yes
+- [ ] No, and this is why: _please replace this line with details on why tests
+      have not been included_
+- [ ] I need help with writing tests
+
+## [optional] Are there any post deployment tasks we need to perform?