Damaged in 1a56b954

For proper syntax highlighting

Closes #3512

Issue #3516

Since foo:bar was matching as a regex (as reported in #2521 but still
occurring for me), limit URI schemes to those in the CommonMark spec
for autolinks http://spec.commonmark.org/0.22/#autolinks

Closes #3513

Not 100% sure that this is the best way to deal with this - but if
you're in an expression, and encounter what you think is a type, it's
probably better to change your assumption and treat it as you would a
variable/constant (Because that's what it probably is) rather than to
forget everything.

I ran the test suite, and it didn't break anything, and the linter,
which was quiet.

Issue #3511

Closes #3504

(not *totally* confident about its correctness, but it looks like a
plausible fix, and seems to work ok)

Closes #3500

I don't know if

1) there's a way to get haxe to, while in functiondef, for instance,
   be able to tell the compiler that what it thought was a type name
   is actually a variable name, and to indent/highlight correctly

or

2) there's a way that, assuming it's a type name, to still indent
   correctly

but it is possible to loosen the lexer to accept things marked as
types as function names (in functiondef), and this fixes the
indentation problem.

Node's 'mime' package gives me text/coffeescript for this.

Closes #3343

Closes #3498

Closes #2962

Closes #3245

Issue #3257

Closes #3386

Issue #3431

Issue #3431

Issue #3431

Closes #3458

Issue #2101

Closes #3494

Closes #3492

Issue #3488

Issue #3487

Issue #3462

Closes #3475