Add an alias `find_triangle` for `jump_and_march`

[DanielVandH]

Inspired by https://github.com/jonocarroll/TriangulArt.jl/issues/12, jump_and_march is a pretty bad name. It doesn't really mean anything to anyone who doesn't already know the name of this specific algorithm. To make it more discoverable, it would be helpful to do

export find_triangle
const find_triangle = jump_and_march

References to the function in the docs for point location should use this new name.