Distinct grammars for the different sh descendants #128

Would be cool to have distinct grammars made available for each of the different sh variants, to help us identify exactly what kind of script we're dealing with. Sometimes a script can run with /usr/bin/sh, sometimes it needs something else!

• POSIX sh
• Thompson sh
• bash (v3, v4)
• ash
• posh
• dash
• zsh
• ksh (mksh, ksh93, ksh98, lksh, pdksh, ...)
• yash