Allowed process substitution as input

[scwatts]

When using a process substitution as input, an error is thrown:

$ prokka <(sed 's/^\(.\+\?\)_length.\+/\1/g' contigs.fasta)
'/dev/fd/63' is not a readable non-empty FASTA file

Changed input file test so that the input must be readable, not a directory, and either a socket or a pipe.