Merge remote-tracking branch 'origin/v2.4' into v2.4

regtest/isdb/rt-fret/Makefile

regtest/isdb/rt-fret/config

regtest/isdb/rt-fret/der2.reference

regtest/isdb/rt-fret/der3.reference

regtest/isdb/rt-fret/der4.reference

regtest/isdb/rt-fret/der5.reference

regtest/isdb/rt-fret/der6.reference

regtest/isdb/rt-fret/der7.reference

regtest/isdb/rt-fret/der8.reference

regtest/isdb/rt-fret/forces.reference

regtest/isdb/rt-fret/plumed.dat

regtest/isdb/rt-fret/trajectory.xyz

regtest/isdb/rt-noe-mi/COLVAR

regtest/isdb/rt-noe-mi/COLVAR.reference

regtest/isdb/rt-noe-mi/Makefile

regtest/isdb/rt-noe-mi/ala12_trajectory.xyz

regtest/isdb/rt-noe-mi/config

regtest/isdb/rt-noe-mi/deriv.reference

regtest/isdb/rt-noe-mi/plumed.dat