Custom SAM tags not always with proper value type

[dominikburri]

At several places, SCINPAS adds custom SAM tags to mapped reads (from BAM files).
The custom tags are set with pysam.set_tag, see documentation here.

Since no value type is given, it is deduced. Sometimes this does not work and e.g. intended integers are set as strings.

This can be circumvented by setting value_type according to our type, which is either integer "i" or string "Z".
It can also be that the value provided is not correct, e.g. a string "1" is provided. This could be changed by providing an actual python integer by e.g. casting it with int("1").