Panopoly Magic only provides node view modes for view mode selection

I marked #1986056: Configuration modal shows wrong stuff for views content pane based on files as a duplicate as the patch here has better code + is more generic.
It doesn't seem to apply against the latest dev though + needs some of the work from the other issue.
Working on it now.

Hmn. It's getting there. I've merged the two issues + have tidied things up a little.
At the moment all is working well I think up until the final bit: rendered entities are not being displayed once the modal is closed.

However, the preview is working now for node, file and user entities. I haven't tested other entity types.
I've clearly broken something though as node entities used to save fine with a view mode selected.

OK. This one works for me.
The problem with entities not rendering after saving is fixed I think.

Improved default view mode (sometimes no default was set).
If teaser is available it is set as the default, if not available then the first view mode returned is set as the default.

Updated patch for 7.x-1.6+2-dev
Also added code to check for old views that have something other than 'fields' or 'table' in settings.
If not 'fields' or 'table' then 'rendered_entity' is used. This is instead of 'nodes' for example.
I didn't just check for nodes as I have a legacy patch which added 'files'.

Here's a new patch. Includes:

- fix to make sure preview defaults to teaser if no view mode is available (otherwise the first time a user views the form with a preview no view mode will be selected and the display will be a bit screwed)
- made this issue dependant on #2274023: Remove trailing whitespace from panopoly_magic.module as it was difficult to patch panopoly_magic.module with trailing whitespace

Adjusted to include view_settings for preview
Still dependant on #2274023: Remove trailing whitespace from panopoly_magic.module

Adjusted to make sure legacy way of storing entity type is changed within panopoly_magic_views_pre_view()

Here is a version of this patch that doesn't depend on #2274023: Remove trailing whitespace from panopoly_magic.module. As explained there, we can't commit coding style changes (including whitespace) until after we've gotten the number of unreviewed patches down. I'll review this patch in a moment!

Ok! I tested and reviewed and made a couple of changes:

• Restored to the original default of "Fields" (rather than "Content")
• Made what the helper functions do a lot clearer
• Minor code-style fixes for the newly added code

I've attached an updated patch and interdiff from the last patch. I ran the tests I thought would be affected locally and they succeeded! I'm going to commit in a moment so that the full test suite will run on Travis-CI.

Thanks so much to @whastings and @Andrew Edwards for your hard work on this patch!

Committed!

Let's see what Travis-CI has to say:
https://travis-ci.org/panopoly/panopoly/builds/29063701

Woohoo! Thanks @dsnopek