Version 2.3.3

Biggest risk of breakage for people updating early:

• File locking strategy just got changed (on Unix) #1886 Thanks @nmandery

Other things:

• Range for Minutes. #1863 Thanks @j-santander
• CORS headers for responses from scheduler. #1870 Thanks @jessicaaustin
• Docs and configurationf for email updated. Finally! #1871 Thanks @daveFNbuck
• Further fixes to Batch running functionality. #1858 Thanks @daveFNbuck

And many more other small improvements. Thanks to everyone who've contributed!