Issue #4787

Since moving the highlighting frontier forward when doing
things like getTokenAt is not safe at all.

Also properly update highlighting frontier when a change
happens.

Closes #4813

This way it can be included more easily with javascript bundlers like
browserify/sheetify

Issue #4809

Issue #4803

Default this to true when the fat-cursor style is active.

Issue #4803

leave the old one for now

Issue #4800

(see grzegorzmazur/yacas#231)

Closes #4785

Closes #4786.

Enums are available in Dotty and soon will be available in Scala.

Addresses #4771

Closes #4774

Closes #4773

So that Doc can do its auto-new trick before calling the
superclass constructor.

Closes #4768

Rather than abusing variable-3. Coloring is the same for now.

Since the vim bindins are depending on that

Closes #4760