MPD protocol: fix upgrading protocol ignoring part of the buffer
MPD protocol: fix upgrading protocol ignoring part of the buffer

closes #146

Also fixed a crash when setting consume on/off

CalebMorris/groovebasin,Qbuer/groovebasin,sammcj/groovebasin,andrewrk/groovebasin,gorlug/groovebasin,sammcj/groovebasin,gorlug/groovebasin,CalebMorris/groovebasin,sammcj/groovebasin,neynah/groovebasin,neynah/groovebasin,emersion/groovebasin,dwrensha/groovebasin,neynah/groovebasin,gorlug/groovebasin,andrewrk/groovebasin,Qbuer/groovebasin,melissanoelle/groovebasin,andrewrk/groovebasin,melissanoelle/groovebasin,dwrensha/groovebasin,emersion/groovebasin,emersion/groovebasin,CalebMorris/groovebasin,dwrensha/groovebasin,dwrensha/groovebasin,Qbuer/groovebasin,melissanoelle/groovebasin