Closes #3834

Issue #3821

Rather than hard-coding the bare XML mode.

Issue #3829

`serializeable` → `serializable`
Replace `an` with `a` 
Remove extra `command`

See https://discuss.codemirror.net/t/any-way-to-override-syntax-error-highlighting-in-asp-net-like-code/642

Closes #3808

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

Issue #3794

Closes #3806

Closes #3802

Closes #3800

Closes #3804

Closes #3797
Closes #3794

Closes #3803

It doesn't work inside of a transformed container, even for zero
transforms (which some components seem to love putting on root
elements, for whichever reason)

Closes #3238

Closes #3791

Issue #3790

Issue #3779

To avoid messing up the position of the gutter when an offset
bigger than the max offset is given.

Closes #3781
Closes #3788

Issue #3624

Closes #3787

Issue #3766

Closes #3777