pmd fix insufficient data after filter

[andrewdavidsmith]

• src/common/TwoStatHMM_PMD.cpp: Formatting code
• src/analysis/pmd.cpp: adding an additional check for sufficient data after filtering bins based on deserts
• src/analysis/pmd.cpp: changing the min required bins for inference to be 100. It's not clear if this is important because the bins after filtering will be sufficient if the data is good, and if this is a problem, the number of bins will be extremely small