every use of BSD4 on hackage is incorrect

[Duncan Coutts]

The following hackage packages specify in their .cabal file:

license: BSD4

Which is the 4-clause BSD license, ie the one with the advertising
clause.

cabal-upload-0.3
Chart-0.5
FiniteMap-0.1
haxr-3000.0.1
haxr-th-1.0
hbeat-0.1
htar-0.1
pcap-0.4.2
tar-0.1.1.1
unix-compat-0.1.2.1

Inspecting the LICENSE files for every one of these packages reveals
that they actually use the 3-clause BSD license. Not a single hackage
package really uses the 4-clause BSD license. In every case that it has
been used it was just a confusion.

We therefore propose to deprecate BSD4 as a valid license in .cabal
files:
http://hackage.haskell.org/trac/hackage/ticket/205

In the unlikely case that anyone really wants to use the 4-clause BSD
license they can still specify "license: OtherLicense" and put the text
in the accompanying LICENSE file.


Additionally, I propose to add the MIT license since there are a couple
packages that really use that and allow optional versions on the
licenses that are versioned, which includes the GPL and LGPL.

Looking at OtherLicense we find common ones are MIT, variations on BSD3
(2 clause and fewer, other informal variations), disjunctions of BSD3 /
GPL (ie dual licensing), conjunctions of BSD3 / GPL (ie some bits user
BSD some under GPL).

Duncan