fixed bug in MultiTimbralManager which didn't 1st stop old sounds when running out of voices
fixed bug in MultiTimbralManager which didn't 1st stop old sounds when running out of voices

--HG--
branch : toxiclibs

ruby-processing/toxiclibs,postspectacular/toxiclibs,rekii/toxiclibs,postspectacular/toxiclibs,rekii/toxiclibs