format_detection finds `ubam` for bgzipped fastq file

[yhoogstrate]

Hi there,

I found a small error in the format detection that marks a bgzipped fastq as unaligned bam.

At the following line:

FastQt/utils/format_detection.cpp

Line 140 in 07da1be

&& static_cast<unsigned char>(magic_number.at(2)) == 2;

There needs to be an additional constraint that parses (using zlibs gzread or the included quagzipfile.h) the first 4 bases from the bgzipped file and ensures it equals [B][A][M][\1]

kind regards,

Youri