Implement changes discussed in #1821
Cherry-picked 4e54cabc5147e3b9e21d640627fd13a0bd3750c2
Made some changes to respect the old logic of the setAttachments method
Make sure all changes from 4e54cabc5147e3b9e21d640627fd13a0bd3750c2 were brought back
Made a terrible mistake. Field in DB use _ not -
If a section is unsorted via ?unsort, then revert to sorting by Entry ID. Fixes #1858
Merge pull request #1866 from DeuxHuitHuit/entry_id

Made a terrible mistake. Fields in DB use `_` not `-`
Merge pull request #1863 from DeuxHuitHuit/fix-1821

Implement email attachment encoding charset. Closes #1821
Fix Author field grouping. Closes #1855
Tweak nested columns in responsive mode to be full width
Merge branch 'integration' of github.com:symphonycms/symphony-2 into integration
Fix the wrong @since version. See https://github.com/symphonycms/symphony-2/pull/1863/files#r7655263
Merge pull request #1867 from DeuxHuitHuit/version-fix

Fix the wrong @since version.