Modern watch command.
Features:
* Basic features of original watch command:
+ Execute command periodically, and display the result.
+ color output.
+ diff highlight.
* Time machine mode:
+ Rewind like video.
+ Go to the past, and back to the future.
* See output in pager.
* Vim like keymaps.
* Search text.
* Suspend and restart execution.
* Run command in precise intervals forcibly.
* Support shell alias
* Customize keymappings.
* Customize color.