[Pkg-rust-maintainers] A few changes in the packaging

[Sylvestre Ledru]

Hello,

I did a few changes on Jordan's version:
* Update the make install logic to install in debian/tmp/
    instead of debian/rust and use the *.install files
* Introduce the rust-doc package
* Building of the latex doc
* Force the verbose mode during the build

Besides the copyright file, for me, it seems ready to be uploaded
(as NEW can take a while, we can still polish the package in between).

Sylvestre