Update readme.md

Adding some notes about how to generate multires images ^_^ (it took me some time to figure it out hehe). 

Thanks by the way for this lib! I love it :D

Extra space not matching the replace condition on build

Hello,

the minified built version of pannellum.htm was not correct cause this space in the replace line was not replacing the corresponding line in src/pannellum.htm

        <link type="text/css" rel="Stylesheet" href="css/pannellum.css"/>

Added option to stop auto rotation after a set delay.

Added a JSON config option to stop autorotate after a certain time (counting from when the autorotate started).

The name of the configuration option is `autoRotateStopAfter` and by default is inactive.

That can be useful for when we want the image to autorotate in a interval (between x and y).

Signed-off-by: Matthew Petroff <matthew@mpetroff.net>