MDL-40262 theme_formal_white: I simply assigned black (that is well contrasted according to http://snook.ca/technical/colour_contrast/colour.html) to links and white (that makes a not compliant contrast with background color) to plain texts in the breadcrumb. This is the less expensive solution I found to differentiate plain text and links and have links well contrasted.
MDL-41117 theme_formal_white: fixed border around header of course categories and sub-categories
MDL-41438 core_renderer: Update the parameters for heading() and heading_with_help().
heading(), change the default value for classes from 'main' to null.
heading_with_help(), add 2 additional parameters for level and classnames. Default value of level is set to 2 and classnames is set to null.

With the changes for heading_with_help(), icon image vertical alignment needs to be adjusted, so it display in the middle of the heading.

Also added some notes in theme/upgrade.txt file.
MDL-41438 core renderer: additional patch to remove .main definition from all core themes
MDL-41497 enrol_database: Added help text for using odbc dsn names instead
MDL-37028 Integrity check for course modules and sections

created function, unittest, build-in quick integrity check on each call to rebuild_course_cache()
also added CLI script
MDL-41508 move_courses() bug fix and DB query improvement
MDL-40733 mod_forum: added the forum name to some pages that were missing it
MDL-41497 auth_db: Added help text for using odbc dsn names instead
MDL-38856 reposition activity group control and fixed titles in chat, database and forum
MDL-40735 mod_lesson: fixed up a header and stripped out hardcoded formatting
MDL-41556 - workshop: undefined constant FILE_INTERNAL message fixed.
MDL-41508 Changes in indentation
MDL-41558 cache: Improve performance of cache::make() by using isset instead of array_key_exist()
MDL-41558 cache: Identifiers should never be passed as null to cache::make()
MDL-23335 mod_forum: allow multi-lang filtering of shortened messages
MDL-37028 Integrity check for course modules and sections

If section mentioned in 'orphaned' module does not exist module is added to the first available section. Also corrected whitespaces
MDL-41565 event: Correct inclusion path of observers includefile
MDL-28561 blocks_rss_client: Fixes lines between RSS feed items are not showing in all themes.
MDL-41305 group: Form improvements for group/grouping creation