Rewrite mapping docs (#308)

* Add overview figure

* Work in progress

* Fix links

* Transform pdfs to svgs

* Update kernel method section

* Also write about GPU executors

* Language edits by Benjamin and Makis

Co-authored-by: Gerasimos Chourdakis <chourdak@in.tum.de>
Co-authored-by: Benjamin Uekermann <benjamin.uekermann@gmail.com>

* Review updates

* Makis language edits

Co-authored-by: Gerasimos Chourdakis <chourdak@in.tum.de>

* Fix typos via aspell

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Co-authored-by: Gerasimos Chourdakis <chourdak@in.tum.de>
Co-authored-by: Benjamin Uekermann <benjamin.uekermann@gmail.com>