Multiply the duration of every element in measure by multiplier. Then rewrite the meter of measure as appropriate.
Return treated measure.
Like magic.
Example:
abjad> t = RigidMeasure((3, 8), construct.scale(3))
abjad> measuretools.scale_and_remeter(t, Rational(2, 3))
abjad> print t.format
\time 3/12
\scaleDurations #'(2 . 3) {
c'8
d'8
e'8
}