Primer 3 option: span exon-intron boundaries

The option should allow to provide an mRNA sequence (or database identifier) to locate exon-intron boundaries within the sequence. After that the user should be able to choose what exons to amplify. If the product of primer doesn't span the exon region than it should be excluded from results.

The similar features are available in:
1) PerlPrimer (http://perlprimer.sourceforge.net/index.html)
2) PrimerBLAST (http://www.ncbi.nlm.nih.gov/tools/primer-blast/)