Don't mess up the display when updateDisplay is given a negative top offset

Issue #2554
[css mode] Add object-fit and object-position properties
[css mode] Better handling of parentheses in property values

Issue #2551
Fix typo in manual
[closetag addon] Improve heuristic for seeing if closing tag already exists

Issue #2557
Make ctrl-drag copy text

Issue #2556
Ensure a viewport always contains a single line
[tern addon] Improve alignment of completion docs
[tern addon] Remove unnecessary error check
[tern addon] Lint fix
[tern addon] Allow hiding and deleting docs by identity, not just name
[vim] Add vim keypress and command done events
[tern addon] When jumping to definition, set a forward selection
[show-hint addon] Fix accidentally renamed option
[real-world uses] Add Montage Studio and Apache GUI
[python mode] Fix indentation-breaking bug

Issue #2503
[python mode] Fix handling of scope end by dedent

Issue #2503
In context menu handler, keep selForContextMenu up to date

So that the added zero-width space doesn't confuse readinput, even
if some other event handler messed with the selection in the meantime.

Issue #2566
Preserve class name added by renderLine event handler

Issue #2564
Add a bias option for selection operations

Issue #2560