Autorefresh

Added an autorefresh option that is enabled by pressing [a] on the current market. This shows as: " › [a]bitstamp   updating... " and refreshes the selected market every 10 seconds. Multiple market can be automatically refreshed.

To cancel, you need to deselect them by pressing [a] again or press enter to deselect all.

TODO: make the 10 seconds customizable. I wanted to use file arguments for this or read the input from CLI, but unfortunately I lack some node skills.