Two node bug fixes

[jribado-IDM]

Identified genetic metric calculation and reporting bugs that affects single and multinode simulations:

• Subpopulation reporting was not appending the year
• Ability to name sampling columns by user name in addition to method
• Updates to summary statistics to account for low sample sizes
• Inclusion of within host IBx summaries to complements Fws calculations at the population level
• Addition of variant filtering to remove non-neutral biallelic variants (ex msp) from the variant array file.

[jribado-IDM]

PR with test fixes already merged - closing this version.