v1.4.7

Overall:

• Images and iFrames are now clearing with the keyboard shortcut
• Reduces latency of ipython executions by 50x.
• Reports the result of checking for auto-updates if the user manually requested a check.
• Removes extra code that was being used to test the auto-detection. It was preventing the persistence of the user's python cmd setting.
• Uses which python as a highly prioritized source of python detection.