a few tiny doc improvements
Part 3: Grammar cleanup on comment in MenuLinkContent todo
Step3: moving weight to the bottom of the form to match head.
START PART 4: https://www.drupal.org/node/2301317
apply patch https://www.drupal.org/files/issues/menu-2256521-conversion-review-do-not-test.patch
and resolve 8.x conflicts
fix hook_uninstall to use the correct service
rename updateLink to updateDefinition
rename deleteLink to removeDefinition
rename isResetable() to isResettable()
convert topLevelOnly() to setTopLevelOnly()
fix destination
another destination fix
partial test fix
rename yml files
add back system block caching
don't eanble menu_link module per Alex
START PART 5: https://www.drupal.org/node/2301319
apply patch https://www.drupal.org/files/issues/menu-2256521-remove-dead-code.patch
and resolve conflicts with 8.x