Bump version to 0.3.7 

Merge pull request #585 from plotters-rs/update-bitmap Bump version to 0.3.6

Bump version to 0.3.5 

Plotters core crate update 

Release tag for Plotters 0.3.2 release 

Plotters 0.3.1 release 

Plotters 0.3.0 release 

Plotters 0.2.15 release 

Plotters 0.2.14 release 

Plotters 0.2.13 release