mm2

mm2 is used at run time in 3 crates.

Number of dependers	mm2 version	Downloads/month
0	0.24.0	81
1	0.23.3	130
2	0.15.1	0

Depender (with downloads and own rev deps)			mm2 version
550	2	asts		^0.23.1
100		csbq		^0.13
		polyNext		^0.13