Or on Windows, it’s Ctrl+Shift+up/down.

Also:

Ctrl+Shift+D duplicates the current line by default (or the current selection, if any). Ctrl+Shift+K deletes the whole line. Ctrl+K twice deletes to end-of-line. Ctrl+K Ctrl+backspace deletes to beginning-of-line.

Combine duplicate, move up/down, and the Ctrl+D multi-cursor stuff, and you have a copy-and-paste coder’s dream editor. ;-)