Error handling when not connected (Flash Red LED by default)

[gfwilliams]

Add flags (E.setFlags) for:

• Flashing Red LED when there's an uncaught error (default on devices with physical LED)
• Writing the Error to Storage (not default)

Which should help catch errors that occur when nothing is connected to the device

[gfwilliams]

... maybe store the error in RAM by default (it can be deleted if more memory is needed like we do for history) and set something in E.getErrorFlags. Then when the Web IDE connects it can check the error flags and output the exception that occurred when nothing was connected