Make line numbers in the editor optional

browser/main/Detail/SnippetNoteDetail.js

@@ -530,6 +530,7 @@ class SnippetNoteDetail extends React.Component {
             fontSize={editorFontSize}
             indentType={config.editor.indentType}
             indentSize={editorIndentSize}
+            lineNumber
             keyMap={config.editor.keyMap}
             onChange={(e) => this.handleCodeChange(index)(e)}
             ref={'code-' + index}

browser/main/lib/ConfigManager.js

@@ -35,6 +35,7 @@ export const DEFAULT_CONFIG = {
     fontFamily: win ? 'Segoe UI' : 'Monaco, Consolas',
     indentType: 'space',
     indentSize: '2',
+    lineNumber: true,
     switchPreview: 'BLUR' // Available value: RIGHTCLICK, BLUR
   },
   preview: {

browser/main/modals/PreferencesModal/UiTab.js

@@ -46,6 +46,7 @@ class UiTab extends React.Component {
         fontFamily: this.refs.editorFontFamily.value,
         indentType: this.refs.editorIndentType.value,
         indentSize: this.refs.editorIndentSize.value,
+        lineNumber: this.refs.editorLineNumber.checked,
         switchPreview: this.refs.editorSwitchPreview.value,
         keyMap: this.refs.editorKeyMap.value
       },
@@ -222,6 +223,17 @@ class UiTab extends React.Component {
             </div>
           </div>
 
+          <div styleName='group-checkBoxSection'>
+            <label>
+              <input onChange={(e) => this.handleUIChange(e)}
+                checked={this.state.config.editor.lineNumber}
+                ref='editorLineNumber'
+                type='checkbox'
+              />&nbsp;
+              Show line numbers in the editor
+            </label>
+          </div>
+
           <div styleName='group-header2'>Preview</div>
           <div styleName='group-section'>
             <div styleName='group-section-label'>