generate_matrix: generate matrix files
In HBP: Hi-C BED File Analysis Pipeline

generate matrix files from HiC-Pro result can be used as following command: generate_matrix(all_hic_file="demo.matrix",all_bed_file="demo.bed",outputpdf="FALSE",matrix_dir="hg19",chrom_file="chrom_hg19.sizes")

`all_hic_file`	the path of hic matrix file generated by HiC-Pro, can be found in the ../hic_result/matrix/myhic/iced/resolution/**_iced.matrix
`all_bed_file`	the path of hic index file generated by HiC-Pro, can be found in the ../hic_result/matrix/myhic/raw/resolution/**_abs.bed
`outputpdf`	the picture format of result, if set FALSE, result will be plotted at JPEG format, if TRUE, result will be ploted at PDF format
`matrix_dir`	the output path of this function.
`chrom_file`	the chromatin information file