MDL-39947 mod_forum: Add safety check to variable assignment when counting unread posts
MDL-39971 each attempt builds on last broken for previews.
MDL-39978 Essays with files break each attempt builds on last
MDL-39820 theme_bootstrapbase: Fix form button alignment for badges.
MDL-40018 theme_sky_high: Fixed footer in admin pages.
MDL-39773 bootstrapbase: add style for .centerpadded.
Relocate .centerpadded styling from standard to base themes
MDL-39964 report_progress: don't browser sniff for SVG support

Use feature detection, its more robust and better practice.
MDL-39940 tags: missing setType call
MDL-25901 rss: do not copyright html tag

They copyright field does not permit html, it should be plain text
MDL-26925 User selector: Set label when no results

Thanks to Jonathon Fowler for the fix!
MDL-39979 navigation: Remove the use of an undefined variable
MDL-40013 Easier to override saving question hints

This adds 3 new methods, called from question_type::save_hints,
to make it easier for different question types to overload this
functionality without duplicating code.

Question types that will benefit from this change include
oumultiresponse, ddmarker, preg and correctwriting.
MDL-39832 Files: Revert MDL-39688 commit, 161be9206571787557eb5c11ee440c9e6ae93ca8

MDL-39688 has been successful in providing a solution for the issue but further
investigations done in MDL-39832 have got the evidence that the given solution
is more likely a workaround.
MDL-39832 Files: Fixed ETag format according with RFC2616.

ETag must be double quoted,
http://tools.ietf.org/html/rfc2616#section-3.11:

      entity-tag = [ weak ] opaque-tag
      weak       = "W/"
      opaque-tag = quoted-string
MDL-39338 core_question: Make history box a .well
MDL-37968 course_overview: add dim class to hidden courses for teachers.
MDL-40088 fixed bug with not visible course section
MDL-32480 fix display of IMS content packages with external links
MDL-32480 allow external https links in IMSCP too
MDL-28394 fix enrolment method restore logic

This patch fixes:
* missing enrolment methods after 1.9 backup restore - defaults are added
* enrolment methods are restored only when users option is enabled
* manual enrolment override option is disabled if users not available