added filenames in error messages of tabix_compress.
added filenames in error messages of tabix_compress.

mattions/pysam,mattions/pysam,daler/pysam,TyberiusPrime/pysam,carolinux/pysam,mattions/pysam,nlhepler/pysam,carolinux/pysam,pysam-developers/pysam,daler/pysam,kyleabeauchamp/pysam,brendanofallon/pysam,kyleabeauchamp/pysam,bioinformed/pysam,bioinformed/pysam,nlhepler/pysam,bioinformed/pysam,mattions/pysam,TyberiusPrime/pysam,nlhepler/pysam,brendanofallon/pysam,brendanofallon/pysam,daler/pysam,TyberiusPrime/pysam,dannon/pysam,kyleabeauchamp/pysam,daler/pysam,pysam-developers/pysam,pysam-developers/pysam,kyleabeauchamp/pysam,brendanofallon/pysam,daler/pysam,dannon/pysam,nlhepler/pysam,bioinformed/pysam,mattions/pysam,brendanofallon/pysam,dannon/pysam,carolinux/pysam,dannon/pysam,kyleabeauchamp/pysam,carolinux/pysam,TyberiusPrime/pysam,carolinux/pysam,TyberiusPrime/pysam,bioinformed/pysam,dannon/pysam,nlhepler/pysam,pysam-developers/pysam