Include `.`s and `?`s in custom operators

[brianrourkeboll]

Many valid custom symbolic operators currently show discontinuous highlighting when they include .s and ?s, e.g.,

+.+
-.-.-
????*????
.&.

Screenshot of GitHub before

This updates the grammar to include contiguous .s and ?s in operator names.[^1]

Before

After

[^1]: The regex still doesn't actually segment operators according to spec, but it's good enough for highlighting.

[baronfel]

Thanks! Sorry for the delay here. working on an Ionide update to include this and other updates now.