Merge branch 'v2.2' into v2.3

regtest/basic/rt80/COLVAR.reference

 #! FIELDS time mu1 phi md.bias
 #! SET min_phi -pi
 #! SET max_phi pi
- 0.000000  1.163  0.497 -0.000
- 0.050000  1.131  0.444 -0.000
- 0.100000  1.098  0.398  0.006
- 0.150000  1.080  0.351  0.000
- 0.200000  1.087  0.314  0.048
+ 0.000000  1.163  0.497  0.000
+ 0.050000  1.131  0.444  0.000
+ 0.100000  1.098  0.398  0.480
+ 0.150000  1.080  0.351  0.934
+ 0.200000  1.087  0.314  1.403