exSTRa v0.88.6

ggplot2 methods work in a limited capacity for exstra_score objects, incorporating x$data and x$sample table columns.

More bug fixes

• plotting the resulting tsum_test() test object no longer tries to access a global tsum variable.
• tsum_p_value_summary() correction parameter works
• some manual page corrections

Some work on making parallel tsum_test() work better, but with only minor benefit.