update ImplicitEquations

drop v0.5 support

update ImplicitEquations

• use Le, Lt, ... instead of Base.<=, Base.< with unicode support via some similar looking operators to defined predicates
• fix plot recipe
• add map option for plotting for specifying a conformal map of the region. Treats (x,y) as the complex plan with x + yi, and draws the image of the region under the map z -> f(z).