Fixed broken nrrd reading / writing.  Specifically, the number of spaced dimensions was defaulting to the total number of dimensions when the header contained neither "space" nor "space dimension" fields.  Now the default is inferred from the "kinds" field. Also, the imwrite function was writing an entry for the temporal dimension in the "space units" field.  This was causing imread to fail, so now "space units" no longer has non-spatial entries.
Fixed broken nrrd reading / writing.  Specifically, the number of spaced dimensions was defaulting to the total number of dimensions when the header contained neither "space" nor "space dimension" fields.  Now the default is inferred from the "kinds" field.
Also, the imwrite function was writing an entry for the temporal dimension in the "space units" field.  This was causing imread to fail, so now "space units" no longer has non-spatial entries.

zhmz90/Images.jl,timholy/Images.jl,JuliaPackageMirrors/Images.jl,c42f/Images.jl,cdsousa/Images.jl,zhmz90/Images.jl,cdsousa/Images.jl,benmoran/Images.jl,twadleigh/Images.jl,twadleigh/Images.jl,c42f/Images.jl,benmoran/Images.jl