Can I add a mobile data shortcut? I want to be able to turn on and off mobile data more easily. Is there any way to add a mobile data widget or to add it to quick setting panel?
If your device meets the following requirements viz.,


  Compatibility
  
  
  Supports AOSP devices running vanilla Android 5.0
  DOES NOT support devices running ROMs vastly modified by device manufacturers (HTC Sense, Samsung Touchwiz, MIUI, LeWa, Xperia, ...)
  SHOULD NOT be used with custom ROMs like CM, AOSPA, RootBox, SlimBean and others - it makes no sense since the most of the features are already in the ROM (may cause conflicts and unexpected behaviour)
  


then consider installing GravityBox [LP]. Note that this app requires your device to be rooted and Xposed Framework installed.

If GravityBox doesn't work for you, then you may install DS Battery Saver. Run it under Off feature and enable its notification. This notification will add a quick launch option for Mobile Data in Notification Drawer. Note that the requirements for this app are same.

However, if you do not want to root your device or install Xposed Framework, then consider looking over these apps by either following this link, or typing Mobile Data in Play Store search and look for apps that allows "On/OFF, Toggle or Widget". They don't generally requires Root access.



GravityBox [LP]


  GravityBox is a module which primary goal is to provide the users of AOSP devices
  with a tweak box to turn their vanilla AOSP ROM into custom ROM packed with additional features and tweaks
  without need to flash anything. Most of the preferences can be changed on-the-fly without rebooting.




Xposed Installer


  Xposed is a framework for modules that can change the behavior of the system and apps without touching any APKs. That's great because it means that modules can work for different versions and even ROMs without any changes (as long as the original code was not changed too much). It's also easy to undo. As all changes are done in the memory, you just need to deactivate the module and reboot to get your original system back. There are many other advantages, but here is just one more: Multiple modules can do changes to the same part of the system or app. With modified APKs, you to decide for one. No way to combine them, unless the author builds multiple APKs with different combinations.




Deep Sleep (DS) Battery Saver


  Deepsleep battery saver constantly puts the device to deepsleep mode while screen off.
  
  LifeHacker: "Plenty of apps save your battery life, but this one takes the idea to a whole new level"
  
  Google Play: download
  
  During deepsleep mode, Wifi, 3G are turned off, background apps are stopped. Therefore, most apps are not working, including Facebook, Google Service, etc,. It then constantly wakes up in order to download email, sync Facebook status, etc,. It's defined by deepsleep frequency and woke up duration