Updated plugin source for VIP compatibility

[bcampeau]

We're ready to submit this plugin to WordPress VIP for inclusion into their plugins repository. In order to do so, I've created this pull request which addresses all of the items likely to get your plugin approved. These include:

• Adding PHPDoc descriptions of all functions
• Fixing incorrect or missing output escaping
• Adding better translation compatibility
• Bringing code formatting up to WordPress PHP standards

I've also incremented the plugin version and added a few useful filters, though I can change that back if you don't wish to do so.

If this looks good, please merge this so I can get the VIP team reviewing it. Don't hesitate to follow up with any questions or comments. This fully addresses #30.

Thanks!

[reefdog]

@bcampeau As you can see, I added a bunch of line notes with individual questions or quibbles. Overall this looks great and I'll be glad to merge it in.

[bcampeau]

I've addressed all your comments. There was some very weird indentation issue with the file. I had to completely zap your existing tabs but all is good now.

[bcampeau]

Just wanted to check in about getting this merged so we can proceed with a VIP review.

Thanks.

[reefdog]

@bcampeau Sorry, dragging a bit on testing this. I'll try to have it merged in today, else tomorrow. Thanks again for your work on this. Added one note above.

[bcampeau]

Thanks. I missed that comment on the oEmbed and I've just fixed it now.

[reefdog]

Super. I'll give it a test today and merge in unless I find problems. Thanks again @bcampeau.

[bcampeau]

Any issues in testing? Thanks.

[reefdog]

@bcampeau No problems from your changes, though I found a few other things I want to fix. Thanks again, shooting for a release this week.

[bcampeau]

Thanks. I've given VIP a heads up ahead of time since it will take some time for them to get this in their queue.