Option to disable the double question mark ?? ligature

[sagi-glacia]

While this ligature may be useful for C#, in rust it is entirely possible to have result_of_result??, where each ? is a distinct operation (performed twice to unwrap a doubly nested type) rather than part of a single logical unit. The current ligature is somewhat detrimental to easy reading in this case.

Please add a variant option to disable combining these glyphs.

(Spectacular font, in general. Excellent work!)