Revert "Upgraded to Macro Paradise 2.0.0-M5; doesn't compile yet, pending fix of https://github.com/scalamacros/paradise/issues/22"

This reverts commit dcdc44298477b1a365a0b9d66eff26ded41cf426.
Upgraded to Macro Paradise 2.0.0-M6
Merge pull request #13 from xeno-by/paradise-2.0.x

Upgraded to Macro Paradise 2.0.0-M6, courtesy of Eugene Burmako (@xeno-by). Thanks!