suggestion to raise a warning for genome assembly version difference UCSC/ENSEMBL

[FatihSarigol]

I was trying to run SICER2 first time and faced a python error that was not informative. Later I noticed in the chromosome list output, the UCSC's chr prefixes which I don't have in the ENSEMBL assembly I used, and I added chr to them all in the bed file, and it worked that time without that error.