Add stylelint and configure eslint to add custom plugin.

- Split up main.ts into multiple files.

src/settings.ts

@@ -0,0 +1,42 @@
+import {App, PluginSettingTab, Setting} from "obsidian";
+import MyPlugin from "./main";
+
+export interface MyPluginSettings {
+	mySetting: string;
+}
+
+export const DEFAULT_SETTINGS: MyPluginSettings = {
+	mySetting: 'default'
+}
+
+export class SampleSettingTab extends PluginSettingTab {
+	plugin: MyPlugin;
+
+	constructor(app: App, plugin: MyPlugin) {
+		super(app, plugin);
+		this.plugin = plugin;
+	}
+
+	display(): void {
+		const {containerEl} = this;
+
+		containerEl.empty();
+
+		containerEl.createEl('h1', {text: 'Settings'});
+
+		new Setting(containerEl).setName("Settings for Sample plugin").setHeading();
+
+		new Setting(containerEl).setName("General settings").setHeading();
+
+		new Setting(containerEl)
+			.setName('Settings #1')
+			.setDesc('It\'s a secret')
+			.addText(text => text
+				.setPlaceholder('Enter your secret')
+				.setValue(this.plugin.settings.mySetting)
+				.onChange(async (value) => {
+					this.plugin.settings.mySetting = value;
+					await this.plugin.saveSettings();
+				}));
+	}
+}