Adopt a new naming scheme to better allign with upstream:

[magnetophon]

faustCompiler is just the compiler, faustTools will be the build scripts
plus environment, and faust will contain both.

[vcunat]

We avoid upper case in names (and in attribute names as well), even if used by upstream. http://nixos.org/nixpkgs/manual/#idm140737319201904 Therefore, faust-compiler should be better. However, both Debian and Fedora call this just faust...

[magnetophon]

The complete NixOS package will be called faust too, but internally it'll be using faust-compiler.

Reason:

faust has quite a lot of optional dependencies, see http://faust.grame.fr/index.php/documentation/references/12-documentation/reference/52-arch-files-reference-art
Most people will only use a subset of these, so people on irc suggested I make two packages.
The other package will depend on this one, and have (most of) the rest of it's dependencies optional.

[vcunat]

Ah, sure. I only saw one faust-related package in nixpkgs, so that confused me.