support hsp tiling without sequences

[tolot27]

For a quick overview of the blast hits it would be helpful to get the tilled hsp statistics without the alignment.

Currently, qseq and sseq must be written to the blast output and mview needs quite a bit of time computing the alignment, especially for larger sequences.

[desmid]

1. Added '-sequences on|off ' option, which disables tiling and output of sequences as well as processing of %identity, %coverage. Moderate speed improvement.

2. Profiled code: largest time spent in i/o routines; another smaller speed improvement made.