add delay parameter for .load

[tonylukasavage]

When loading an external JS file into the REPL, it will be loaded as fast as possible, printing everything to the screen. It would be cool for things like automated demos if you could delay each line by a specific number of milliseconds. For example, the following should load /path/to/file.js waiting 1 second in between each line.

$ triple
> .load /path/to/file.js 1000

[jhaynie]

i also added support for both URLs and files.