Fix #210 mlt_playlist_mix() drops single frame trimmed clips.
Fix #210 mlt_playlist_mix() drops single frame trimmed clips.

j-b-m/mlt,j-b-m/mlt,mltframework/mlt,mltframework/mlt,siddharudh/mlt,mltframework/mlt,mltframework/mlt,j-b-m/mlt,mltframework/mlt,siddharudh/mlt,siddharudh/mlt,mltframework/mlt,siddharudh/mlt,mltframework/mlt,mltframework/mlt,j-b-m/mlt,j-b-m/mlt,siddharudh/mlt,siddharudh/mlt,j-b-m/mlt,siddharudh/mlt,mltframework/mlt,j-b-m/mlt,siddharudh/mlt,j-b-m/mlt,j-b-m/mlt,siddharudh/mlt,mltframework/mlt,j-b-m/mlt