Update monoid-extras version bounds (refs #34)
fix shadowing warning
bump version to 0.7, and bump -core and -lib deps
update contributors and copyright [ci skip]
CHANGES for 0.7 [ci skip]
set transparent fill for lines (fixes #35)
update tested-with field: dropping support for 7.0 and 7.2 [ci skip]
add release date [ci skip]