Support genomic track to phase compartments

[js2264]

Rather than using BSgenome or DNAStringSet, one should be able to provide a bigwig track (imported as RleList) to sign eigenvectors when annotating compartments with get compartments function, eg a coverage track of the GC content.

[js2264]

In the test for phasing with coverage track, use a coverage track of GC content (calculated from the yeast genomic sequence, and smoothed along chromosomes with a bon width of 100)