Akoutmos adding table support

[PragTob]

Follow up to #369

• Some naming/code changes
• Only render out data from measurements that have actually been taken, seems like a good idea
  • add some functions to support operating over all the data/just the used data more smoothly
• change order slightly so we preserve run time, memory, reductions

[PragTob]

So, with benchee's very optimistic support goals dating back to elixir 1.6 we're clashing with table that used __STACKTRACE__ introduced in 1.7.

So options are:

• spin out as a separate package after all
• fiddle with CI to not attempt to install table on unsupported versions