Implement CSW format

[stefanschramm]

https://acorn.huininga.nl/pub/unsorted/software/pc/CSW/csw.html

http://cngsoft.no-ip.org/csw2cdt.htm

https://acorn.huininga.nl/pub/unsorted/software/pc/CSW%20Viewer/How%20to%20record%20WAV%20files%20for%20conversion%20to%20CSW.pdf

http://cngsoft.no-ip.org/csw2cdt.htm

https://github.com/MartianGirl/SpecIde/blob/master/source/src/CSWFile.h
https://github.com/MartianGirl/SpecIde/blob/master/source/src/CSWFile.cc