tiny-count: BAM support

[AlexTate]

BAM files are now supported. This PR also improves the routine that examines alignment file headers to ensure that they have compatible order.

• Strictly compatible @HD headers are SO:queryname or GO:query
• Strictly incompatible @HD headers are SO:coordinate or GO:reference (-> error)
• Files with ambiguous @HD headers (SO:unsorted, SO:unknown, or GO:none) will have the last @PG header inspected as a fallback. If it reports anything other than Bowtie, Bowtie2, or STAR, it is an error. This is because these tools follow the multi-mapping adjacency convention by default (though this list is incomplete)

Additionally, the Samples Sheet is more thoroughly validated during tiny-count standalone runs. The Normalization column is also validated at pipeline startup during end-to-end runs

Closes #302

[taimontgomery]

Tested with Lib303 comparing sam and bam input files from tinyRNA output (collapsed or decollapsed). We might want to note in the documentation that the "Assigned Reads" reported depends on genomic and feature hit normalization.