When hovering a line with multiple lint annotations, codeMirror will
now show all the attached markers instead of just the first one

Closes #3847

This patch enables styling of active line numbers by
adding a `CodeMirror-activeline-gutter` class to the
line's gutter space.

Closes #3802

When enabled, and the annotatescrollbar addon is loaded, matches will
be shown on the scrollbar.

Since the viewport info isn't updated until the redraw, and the event
fires before the redraw.

See https://discuss.codemirror.net/t/whats-wrong-fold-gutters-do-not-show-up-after-swapdoc-call/580

Issue #3733

To avoid IE8 parser issue.

Issue #3636
Issue #3698

Closes #3703

So that tiny mouse motions don't keep resetting the selected item

Closes #3698

Issue #3682

Closes #3651

Make this the default

Issue #3636

Moving the mouse will change the selected hint option

So that the annotations still make sense when scrollPastEnd is enabled

Closes #3630

Issue ternjs/tern#668

Since collapsing might move previously hidden code into the viewport

Issue #3599

Issue #3593

Closes #3548

Closes #3549

Issue #3548

Issue #3525

Issue #3525

Closes #3538

Issue #3518

Right now if you have a selection, and you enter a bracket/quote,
surrounds it with quotation marks, and selects the entire quote. This
change should change the behaviour to selecting the interior of the
quote instead.

The motivating example for me was autocomplete, where after
autocompleting a function the arguments are selected, so if you want
to insert a string literal right now you have to delete the selection
before you can enter the quotes. With the proposed fix, it'll be
rather more fluid.