Focus text input contents on focus

Clicking on the foreground and background text inputs with the mouse, this now automatically selects the entire contents of the input (as happens aleady for keyboard users when they set focus to it). This facilitates going in to edit/type colors...

src/views/js/main.js

@@ -60,6 +60,8 @@ function initEvents () {
  document.querySelector('#background-color .rgb').onclick = function() {showHide(this)}
  document.querySelector('#foreground-color input').oninput = function() {validateForegroundText(this.value)}
  document.querySelector('#background-color input').oninput = function() {validateBackgroundText(this.value)}
+ document.querySelector('#foreground-color input').onfocus = function() {this.select()}
+ document.querySelector('#background-color input').onfocus = function() {this.select()}
  document.querySelector('#foreground-color input').onblur = function() {leaveText('foreground', this)}
  document.querySelector('#background-color input').onblur = function() {leaveText('background', this)}
  document.querySelector('#foreground-color .switch').onclick = function() {ipcRenderer.send('switchColors')}