cabal list should make it clear that a package is old/deprecated

[Fuuzetsu]

So we just had someone in #yi install a deprecated package (marked as deprecated) from 2008:

<alanz> cabal list yi gives the following
<alanz> * yi-gtk
<alanz>     Synopsis: The Haskell-Scriptable Editor, helper package
<alanz>     Default available version: 0.3
<alanz>     Installed versions: 0.3
<alanz>     Homepage: http://haskell.org/haskellwiki/Yi
<alanz>     License:  GPL
<alanz> Nothing about deprecation, or date

It seems to me that cabal should make at least some attempt to communicate that this may in fact not be the right package to install.

[ezyang]

Should we hide the deprecated packages by default? That seems like the most friendly thing to me.

[23Skidoo]

Main problem here seems to be that the information about whether the package is deprecated is not available inside D.C.List. In general, deprecating a package on Hackage currently has no effect on cabal-install behaviour.

To fix this we need to modify both cabal-install and hackage-server:

1. Hackage server should serve a file containing a list of deprecated packages inside the index tarball (similar to preferred-versions).
2. In cabal-install code there should be a flag inside the SourcePackage record specifying whether a package is deprecated.

[jneira]

re #1518 where an user ask for a warning when building a deprecated package, so other way, more direct of communicate the fact
it would need some of the changed described above