Fix an issue with properties view

If a control changed the properties layout, it would lose focus on the
control.  Also, fiddled with the sizing policy a bit, because it wasn't
expanding when I used it in other windows.
Add obs_data JSON loading/saving functions
obs-studio UI:  Implement stream settings UI

 - Updated the services API so that it links up with an output and
   the output gets data from that service rather than via settings.
   This allows the service context to have control over how an output is
   used, and makes it so that the URL/key/etc isn't necessarily some
   static setting.

   Also, if the service is attached to an output, it will stick around
   until the output is destroyed.

 - The settings interface has been updated so that it can allow the
   usage of service plugins.  What this means is that now you can create
   a service plugin that can control aspects of the stream, and it
   allows each service to create their own user interface if they create
   a service plugin module.

 - Testing out saving of current service information.  Saves/loads from
   JSON in to obs_data_t, seems to be working quite nicely, and the
   service object information is saved/preserved on exit, and loaded
   again on startup.

 - I agonized over the settings user interface for days, and eventually
   I just decided that the only way that users weren't going to be
   fumbling over options was to split up the settings in to simple/basic
   output, pre-configured, and then advanced for advanced use (such as
   multiple outputs or services, which I'll implement later).

   This was particularly painful to really design right, I wanted more
   features and wanted to include everything in one interface but
   ultimately just realized from experience that users are just not
   technically knowledgable about it and will end up fumbling with the
   settings rather than getting things done.

   Basically, what this means is that casual users only have to enter in
   about 3 things to configure their stream:  Stream key, audio bitrate,
   and video bitrate.  I am really happy with this interface for those
   types of users, but it definitely won't be sufficient for advanced
   usage or for custom outputs, so that stuff will have to be separated.

 - Improved the JSON usage for the 'common streaming services' context,
   I realized that JSON arrays are there to ensure sorting, while
   forgetting that general items are optimized for hashing.  So
   basically I'm just using arrays now to sort items in it.