nanshe/io/xtiff.py: Make it optional to memory map TIFF files (by default this is false as it is slower).
nanshe/io/xtiff.py: Make it optional to memory map TIFF files (by default this is false as it is slower).

jakirkham/nanshe,nanshe-org/nanshe,DudLab/nanshe,jakirkham/nanshe,nanshe-org/nanshe,DudLab/nanshe