Translate gene

[jpjarnoux]

Two things have been done here:

1. Added the ability to write the translated sequence of all genes using MMSeqs2 with the --proteins option, which works like the other options in the ppanggolin fasta command.
2. In MSA, if the gene sequence length is not divisible by 3, PPanGGOLiN prints a warning message. To be more flexible, the last one or two nucleotides are deleted if the sequence size is not modulo 3. A debug message will issued the partial genes.

[jpjarnoux]

MMseqs2 create db must be forced in mode 1. So in translate_genes we must force the mode.