WriteBM: save .bm files
In aultsch/DataIO: IO Handling for Files Containing Data

Save bestmatches to a .bm file.

1	WriteBM(FileName, BestMatches, OutDirectory = getwd(), Lines, Columns, IsToroid,Comment )

`FileName`	Filename of .bm file
`BestMatches`	2-3 column integer matrix with key, row, column. If there are 2 columns, these should be only bestmatches and key is generated. If there are 3 columns, it is assumed that the first column is key, then: Bestmatches = [BMkey, BMLineCoords, BMColCoords] In cartesian coordinate system the y-axis equals GridHeight - BMLineCoords and the x-axis BMColCoords-1, if only integer values are used
`OutDirectory`	Optional: directory where the file is being written, default is the current working directory
`Lines`	Optional: number of ESOM Rows, Lines= max(BestMatches(:,2) if not given
`Columns`	Optional: number of ESOM columns, Columns= max(BestMatches(:,3) if not given
`IsToroid`	used topology, either 0=planar or 1=toroid
`Comment`	array of characters to be written in the first line of the file, it will be marked with `'\#'`, more than one line, use `'\n#'` Not More than 3 seperate Lines of Comments allowed