Fix some typo in method names, variables
compatability => compatibility
Merge pull request #10761 from vipulnsward/fix-typo-1

Fix some typo in method names, variables
Merge pull request #10762 from vipulnsward/change_compatibility

compatability => compatibility
add test-case for `Array#to_sentence with blank items.
Merge pull request #10763 from senny/10758_to_sentence_with_blank_elements

test-case for `Array#to_sentence` with `blank?` items.
cleanup whitespace in `active_record/relation.rb`.
`implicit_readonly` is being removed in favor of calling `readonly` explicitly
Merge pull request #10769 from senny/10615_join_should_not_return_readonly_records

using `#joins` does not imply `readonly = true`.