produce one single CSV with F90, F91, F93 and SVFS

produce one single CSV with F90, F91, F93 and SVFS, instead of serveral ones,

Based on @mschleiss feedback on #16 (closed)

Having separate files for F90, F91, F93 and SVFS has pros/cons. On the pro side, it makes it easier for humans to check the files. The major drawback is that it creates a lot of files, which is something we don't really want to have because it makes reading/copying/sharing data slower and coding tasks more complicated. Also, when dealing with different files, we constantly have to worry about the fact that the timetables could (potentially) not be aligned. For example, if for some reason, the F90 files contains one line more/less than the F91 file, we would have to run additional scripts to figure out which measurements are missing and realign everything. In my opinion, we should have one file for F61 and one for the rest (SVFS + F90 + F91 + F93).