Automatically use "sourcedialog" plugin/button instead of "sourcearea" plugin/button when using CKEditor for in-place editing

Note that this increases the CKEditor requirements: CKEditor 4.1 MUST be used, and it MUST include the "sourcedialog" plugin. README updated.

Same screenshots as at #1964316-1: Automatically use "sourcedialog" plugin/button instead of "sourcearea" plugin/button when using CKEditor for in-place editing apply:

Back-end:

Front-end (in-place editing), BEFORE patch:

Front-end (in-place editing), AFTER patch:

For the record, this was pointed out at #1906490-20: Default CKEditor toolbar used instead of the CKEditor profile because toolbar configuration not a JS Array. I had intended for this to work this way, but I'd honestly forgotten about it.

Yes, that is by design.

Great point about mentioning the version number in the README. I'll definitely do that before commit.

#1964316: Automatically use "sourcedialog" plugin/button instead of "sourcearea" plugin/button when using CKEditor for in-place editing landed, this should be committed. The CKE 4.1 dependency should be documented, and preferably also tested in the status report.

That was wrong for a while now.

That was wrong for a while now.

Now implemented, and includes a hook_requirements() addition to automatically check this requirement, but only if the site is actually using the "Source" button.

http://drupalcode.org/project/edit.git/commit/eac85f5

Fixed small mistake: http://drupalcode.org/project/edit.git/commit/0675f74