Strip newlines/whitespace from code

[ashfurrow]

Code blocks like this come out with extra whitespace around them:

//// Page whatever

doSomething()

/*:
 Text
*/

Is translated to:

doSomething()

With extra newlines at the bottom.

A PR fixing this issue should strip whitespace from the beginning/end of a page's code.

[ashfurrow]

Looks like Swift Playgrounds automatically strips whitespace from the beginning/end of a file, which is handy.

[ashfurrow]

So basically we'd need to strip the page contents of any newlines that exist adjacent to markdown blocks. Examples:

//:

/*:

 */

Should be doable with regexes, needs to be well-tested.