Important and nice options for homology search

Added control over DIAMOND search

--diamond-mode accepts six options (by decreasing search time and increasing sensibility): fast, mid_sensitive, sensitive, more_sensitive, very_sensitive and ultra_sensitive.
Helps to dramatically decrease search times, but also reduce memory usage and apparently disk usage as well (no ideia why this one).

Added parameter for max memory

Set with --max-memory, read as float in Gb.
Allows to calculate DIAMOND parameters b and c automatically.

Also two small bug fixes

Fixed the case where database was inputted with --skip-db-check and as a FASTA file - UPIMAPI would input the FASTA database directly to DIAMOND.
Fixed outputting days as float. Days don't float.