Added spotless and CONTRIBUTING.md (#172)

CONTRIBUTING.md

@@ -0,0 +1,73 @@
+# Contributing to SlimeVR
+
+This document describes essential knowledge for contributors to SlimeVR.
+
+## How to get started
+
+### Getting the code
+First, clone the codebase using `git`. If you don't have `git` installed, go install it.
+
+```bash
+# Clone repositories
+git clone --recursive https://github.com/SlimeVR/SlimeVR-Server.git
+
+# Enter the directory of the codebase
+cd SlimeVR-Server
+```
+
+Now you can open the codebase in your favorite IDE or text editor.
+
+### Building the code
+The code is built with `gradle`, a cli tool that manages java projects and their
+dependencies. You can build the code with `./gradlew build` and run it with
+`./gradlew run`.
+
+
+## Code Style
+Code is autoformatted with [spotless](https://github.com/diffplug/spotless/tree/main/plugin-gradle).
+Code is checked for autoformatting whenever you build, but you can also run
+`./gradlew spotlessCheck` if you prefer.
+
+To autoformat your code from the command line, you can run `./gradlew spotlessApply`.
+We recommend installing support for spotless in your IDE of choice, and formatting
+whenever you save a file, to make things easy.
+
+If you need to prevent autoformatting for a particular region of code, use
+`// @formatter:off` and `// @formatter:on`
+
+### Setting up spotless in VSCode
+* Install the `richardwillis.vscode-spotless-gradle` extension
+* Add the following to your workspace settings, at `.vscode/settings.json`:
+```json
+"spotlessGradle.format.enable": true,
+"editor.formatOnSave": true,
+"[java]": {
+	"editor.defaultFormatter": "richardwillis.vscode-spotless-gradle"
+}
+```
+
+### Setting up spotless for IntelliJ
+* Install https://plugins.jetbrains.com/plugin/18321-spotless-gradle.
+* Turn on [formatting on save](https://www.jetbrains.com/help/idea/reformat-and-rearrange-code.html#reformat-on-save).
+
+### Setting up Eclipse autoformatting
+Import the formatting settings defined in `spotless.xml`, like this:
+* Go to `File > Properties`, then `Java Code Style > Formatter`
+* Check `Enable project specific settings`
+* Click `Import`, then open `spotless.xml`, then `Apply`
+* Go to `Java Editor > Save Actions`
+* Select `Enable project specific settings`, `Perform the selected actions on save`,
+`Format source code`, `Format all lines`
+
+Eclipse will only do a subset of the checks in `spotless`, so you may still want to do
+`./gradlew spotlessApply` if you ever see an error from spotless.
+
+## Code Licensing
+SlimeVR uses an MIT license, and some parts of the project use a dual MIT/Apache 2.0
+license. Be sure that any code that you reference, or dependencies you add, are
+compatible with these licenses. `GPL-v3` for example is not compatible because it
+requires any and all code that depends on it to *also* be licensed under `GPL-v3`.
+
+## Discord
+We use discord *a lot* to coordinate and discuss development. Come join us at
+https://discord.gg/SlimeVR!