BLAST database extensions

Not all extensions are taken into account in BLAST dialogs when "Select a database file" button is used, e.g. when a user select a .phd file of the database loaded from NCBI, an error occurs as the database name is incorrectly determined.

The database consists of files with the following extensions:
.phd, .phr, .pnd, .pog, .ppi, .psi, .phi, .pin, .pni, .ppd, .psd, .psq, .pal

Make the corresponding changes, if required, for nucleotide databases.