Changed a few things in sphere, cylinder and functions.#10

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pierrebai wants to merge 4 commits intofogleman:masterfrom

pierrebai:master

Commits on Feb 25, 2016

Added top and bottom circle to the cylinder.
Pierre
committed
Added multiple rendering to sphere and made the paths variation have cler names.
Pierre
committed
Added new function Paths, make its Paths function pluggable, updated the example.
Pierre
committed
Made function variations be separate types, put back a check in random vector.
Pierre B
committed