Fix for null mimetypes in os_files alter #3513

Made sure to check if a mimetype was null before array merging it.  When they are empty, use the array we would have merged with.
Merge branch 'SCHOLAR-3.x' into 3513-os_files_null_merge

Conflicts:
	openscholar/modules/os/modules/os_files/os_files.module
sort extensions alphabetically
fields extensions.
more fields.
fix media gallery
Merge branch 'SCHOLAR-3.x' into 3513-os_files_null_merge

Conflicts:
	openscholar/modules/os/modules/os_files/os_files.module
Start work on the UX of event registration.
Add TODO.
Merge branch 'SCHOLAR-3.x' into 4365.
all file types allowed in all file fields besides image fields.
Add update hook to modify variable value for enabled presets #4431
Merge branch 'SCHOLAR-3.x' into 4284
Hiding the registration form on the event page.
Fix a minor error.
Adding a theme for the epoxrt links.
Adding title callback and adding a theme for the export links.
Merge branch 'SCHOLAR-3.x' into 4365
Fixing the access argument.
Add the event registration form to mollom form protection list after enabling.