- force lower-case layer names to allow CIF/MAG loop (CIF needs
upper-case layer names, MAG doesn't)
- reverted CIF reader to standard
- new options for writer: tech, "zero timestamp".
- file name MUST be consistent with one cell name.
Reason: it's not possible to derive the initial
cell from the given options, so without the file name
being consistent, we can't know what to write there.
Basically the file name rather supplies the path.
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