Rename Duktape shortcuts from "DUK 20" to "DUK 2.0" & "DUK 21" to "DUK 2.1"
Rename Duktape shortcuts from "DUK 20" to "DUK 2.0" & "DUK 21" to "DUK 2.1"

The previous versions were incorrect. Lots of engines have high major version
numbers so version 21 sounded plausible.

Delapouite/compat-table,mzgol/compat-table,Delapouite/compat-table,mzgol/compat-table