help user generate enzyme file
the restriction enzyme name.
the restriction enzyme cutting sites
the chromatin information file
the output dir of this function
5' overhangs on the DNA resulted from the cutting
the name of genome
this function is used to generate restriction fragment annotation files. and some annotation files were generated in https://github.com/hechao0407/HBP/tree/master/annotation
can be used as following command: generate_enzyme_file(enzyme="DpnII",enzymesite="GATC",chrom_file="chrom_dm3.sizes",enzymedir="annotation",enzymeoverhangs5=0,genomeName="dm3")