Function image generation

Most functions should have specific images in a given context. For example, `sin` and `cos` should be between -1 and 1 inclusive, given a real argument.

The current implementation is currently very hacky, *requiring* a subtype `T <: AbstractContext` to implement `image(fn::Fn, ::T)`. An implementation which allows for data to be fed into an existing subtype would be more ideal.

Start by reading the current image(fn::Fn, ::T) implementation and the AbstractContext subtype requirements. Investigate how existing contexts could accept supplied data while preserving context-specific images such as sin and cos ranges. Done means the implementation no longer requires each subtype to define the method and supports the stated function-image behavior.

Written by the indexing model from the issue text.