MDL-48243 theme_bootstrapbase: Fixed inconsistancy between LTR/RTL LESS
MDL-48235 mod_assign: Fix reopen until pass behavior
MDL-36673 mod_lesson: slideshow mode not working
MDL-48347 gradebook: Single view shows all grade items.

Manual grade items, course totals, and categroy totals
were not being displayed in the single view.
MDL-44088 ajax: Final deprecation of ajaxenabled() php function
MDL-48169 themes: extra upgrade notes
MDL-48347 gradebook: More behat tests for single view.
MDL-44918 libraries: Final deprecation of count_login_failures()
MDL-48532 core_roles: Set correct heading on user roles page
MDL-43902 output: Final deprecation of classes r0/r1 in table rows
MDL-45295 core_block: Removing obsolete method preferred_width()
MDL-47694 mod_assign: Grades require a grade to show as graded

Special thanks to Howard Miller.
MDL-42862 behat: update deprecated_message api

Deprecated message api now accepts a $throwexception param that if set to true always throws an exception
MDL-48547 thirdparty: remove incorrect entry
MDL-45955 forms: replaced labels in static text elements
MDL-42862 behat: Final deprecation of various steps
MDL-44985 libraries: Final deprecation of conditional classes and apis
MDL-44985 libraries: Final deprecation of conditional apis in modinfo
MDL-34550 libraries: Final deprecation - get_context_instance_by_id()
MDL-48556 backup: Use correct conditions before checking dir permissions