Call by :
julia Jl2pluto [-f] inputfile.jl [outputplutonb.jl]
If unspecified, outputplutonb.jl defaults to "inputfile-pluto.jl"
If no "-f", do not overwrite existing output notebook
If "-f", force write output notebook, erasing it if already existing
Call by :
julia Plutojl2jl.jl [-h] [-i] [-f] [-k] inputplutonb.jl [output.jl]
If "output.jl" unspecified and no "-i", aborts.
If "-i", do the conversion inplace (so, also assume "-f")
If [no "-i and ] no "-f", do not overwrite existing "output.jl"
If "-f", force write "output.jl", erasing it if already existing
If "-k" keep one blank line between cells (else delete both two blank lines between cells)