mapping2exon: This function maps on exon-level Probe Selection Region (PSR) starting for the file produced by function
oneChannelGUI: Mapping exon level probe sets to Reference Sequences
Description
This function retrieve from RRE the PSR sequences associated to the exon-level probe sets
and all exons associated to the gene associated to PRS. Subsequently identify the exon where PSR maps and procuces a
fasta file were are located exon-level PSR and target exon.
The mapping is done using the countPattern function of the Biostrings package. Up to three mismathces are allowed in PSR
mapping on exonic sequence.