add MD_SINGLETON macros
add MD_SINGLETON macros

sidward/bart,mrirecon/bart,sidward/bart,sdimoudi/bart,mrirecon/bart,sdimoudi/bart,sidward/bart,Takishima/bart,sidward/bart,sdimoudi/bart,Takishima/bart,mrirecon/bart,Takishima/bart,Takishima/bart,sdimoudi/bart,sidward/bart,mrirecon/bart,Takishima/bart,sdimoudi/bart,mrirecon/bart