chore: init open-wc component project

This project uses the open-wc.org recommendations and was generated
using their generator https://open-wc.org/docs/development/generator

.editorconfig

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+root = true
+
+[*]
+
+indent_style = space
+indent_size = 2
+
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.json]
+indent_size = 2
+
+[*.{html,js,md}]
+block_comment_start = /**
+block_comment = *
+block_comment_end = */

.github/workflows/test-on-pr-branch.yml

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+name: Test on PR branch
+on: pull_request
+
+jobs:
+  test-on-pr-branch:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '16'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm run-script test

.github/workflows/test.yml

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+name: Test
+on: push
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '16'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm run-script test

.gitignore

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+## npm
+/node_modules/
+/npm-debug.log
+
+## testing
+/coverage/
+
+# build
+/dist
+/custom-elements.json
+/.tsbuildinfo

README.md

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+# OpenSCD Core
+## \<open-scd>
+
+## Installation
+
+```sh
+npm i open-scd
+```
+
+## Usage
+
+```html
+<script type="module">
+  import 'open-scd/open-scd.js';
+</script>
+
+<open-scd></open-scd>
+```
+
+## Linting and formatting
+
+To scan the project for linting and formatting errors, run
+
+```sh
+npm run lint
+```
+
+To automatically fix linting and formatting errors, run
+
+```sh
+npm run format
+```
+
+We use ESLint and Prettier for linting and formatting. Plugins for automatic
+formatting and linting during editing are available for vim, emacs, VSCode,
+and all popular IDEs.
+
+## Testing with Web Test Runner
+
+To execute a single test run:
+
+```sh
+npm test
+```
+
+To run the tests in interactive watch mode run:
+
+```sh
+npm run test:watch
+```
+
+## Tooling configs
+
+For most of the tools, the configuration is in the `package.json` to reduce the
+amount of files in the project.
+
+## Local Demo with `web-dev-server`
+
+```sh
+npm start
+```
+
+To run a local development server that serves the basic demo located in `demo/index.html`
+
+> This webcomponent follows the [open-wc](https://github.com/open-wc/open-wc) recommendation.
+
+## License
+
+This project is licensed under the [Apache License 2.0](LICENSE).
+
+&copy; 2022 OMICRON electronics GmbH

demo/index.html

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+<title>OpenSCD Core Demo</title>
+<open-scd></open-scd>
+
+<script type="module">
+import '../dist/open-scd.js';
+</script>

open-scd.ts

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+import { LitElement } from 'lit';
+
+window.customElements.define('open-scd', LitElement);