MDL-38555 forms: Prevent same data submission multiple times.

This disables Submit button when the form has been submitted to
prevent consequent submissions before the page has been loaded.
MDL-38545 Reports: PHP Strict Standards error in graph.php
MDL-26120 mod_forum: use correct object
MDL-32898 Final deprecation of moodle_strtolower()
 MDL-34508 Formslib: Removed deprecated setHelpButton() from editor.php and hidden.php
MDL-33379 course: Removed deprecated move_section() from course/lib.php
MDL-35666 remove uninstall protocol option
MDL-39166 auth_ldap Add triggers for user created/updated events.
MDL-39409 auth/cas pass web proxy settings along to phpCAS
MDL-39040 - mod_data: Database description available in add entry tab.
MDL-39040 - mod_data: Database description available in single view tab.
MDL-39454 Accesslib: is_siteadmin is a bit slow
MDL-39449 course view.php: don't require forum lib.php

As far as I can see, it is not used, except in social course format, so
I moved the include there.
MDL-39490 Inform the developer about incorrect order of text processing

Before calling format_text(), the text must be processed with
file_rewrite_pluginfile_urls(). This order is important
for some text filters that look for valid pluginfile.php URLs.
MDL-39472 MUC: Optimise cache::get_from_persist_cache
MDL-36482 activities block: Allow mod display without intro's
MDL-39198 theme_formal_white: resized and relocated the "Add..." drop down menu of the "Add a block" pseudo block
MDL-39155 Quiz: Provide 3 image-size options on the settings page
MDL-39630 theme_afterburner: Improving the way course/category listings display.
MDL-38019 Log filter enable/disable