Add {wait##} support to keyboard.click

[dkrutsko]

Applications like Packer give you the option to wait a certain amount of time before clicking the next couple keys, it would be cool to support this in keyboard.click. Might have to extend Keyboard::compile to get this to work.

See all the on/off variant which might be useful to implement.

Additionally, sometimes a constant might not be provided by robot so a generic key such as {key12} would be useful to define where the number is any number which would be directly sent to the operating system.