AnnData to FCS converter

[LuLeom]

Some of the methods strictly require FCS file format as input.
In order to run those methods a functionality that convert AnnData objects to FCS files is needed.

[rcannood]

I think these are all R methods right? We can store helper functions as separate R helper functions and add them as resources

[LuLeom]

Correct, these are all R methods.

I already have a working script for conversion, although it just creates 'plain' fcs files with only markers expression.

(I wonder if some other kind of metadata needs to be written on the fcs file, but I do not see the added value of implementing that for the time being).