Parse multiple rsids

[MalinAhlberg]

Describe the pull request:

• Bug fix
• Functional change
• New feature
• Code cleanup
• Build system change
• Documentation change
• Language translation

Pull request long description:

For lines with more than one variant, eg:

22 16577044 rs374006257;rs200929253 TG AG,T

use the first rsid for the first variation, the second rsid for the second variation, and so on:

rs374006257: TG->AG
rs200929253: AG->T

For

2 16879601 rs371560503 T TA,TAA

we get

rs371560503: T->TA
rs371560503: T->TAA

[talavis]

Looks to me like it should keep the same result for the "real" datasets, so should be fine. Not tested.