Re-license almost all of libVLC and libVLCcore to LGPLv2.1+

This move was authorized by the developers, either:
 - by e-mail,
 - by vote at the VideoLAN Dev Days 2011,
 - on the license website,
 - in a contract, oral or written.
No objection was raised, so far.

The developers agreeing are:
  Justus Piater
  Alexis Ballier
  Alexander Bethke
  Mohammed Adnène Trojette
  Alex Converse
  Alexey Sokolov
  Alexis de Lattre
  Andre Pang
  Anthony Loiseau
  Cyril Deguet
  André Weber
  Boris Dorès
  Brieuc Jeunhomme
  Benjamin Drung
  Hugo Beauzée-Luyssen
  Benoit Steiner
  Benjamin Pracht
  Bernie Purcell
  Przemyslaw Fiala
  Arnaud de Bossoreille de Ribou
  Brad Smith
  Nick Briggs
  Christopher Rath
  Christophe Courtaut
  Christopher Mueller
  Clement Chesnin
  Andres Krapf
  Damien Fouilleul
  David Flynn
  Sebastien Zwickert
  Antoine Cellerier
  Jérôme Decoodt
  Jérome Decoodt
  Dylan Yudaken
  Eduard Babayan
  Eugenio Jarosiewicz
  Elliot Murphy
  Eric Petit
  Erwan Tulou
  Etienne Membrives
  Ludovic Fauvet
  Fabio Ritrovato
  Tobias Güntner
  Jakub Wieczorek
  Frédéric Crozat
  Francois Cartegnie
  Laurent Aimar
  Florian G. Pflug
  Felix Paul Kühne
  Frank Enderle
  Rafaël Carré
  Simon Latapie
  Gildas Bazin
  Geoffroy Couprie
  Julien / Gellule
  Gildas Bazin
  Arnaud Schauly
  Toralf Niebuhr
  Vicente Jimenez Aguilar
  Derk-Jan Hartman
  Henri Fallon
  Ilkka Ollakka
  Olivier Teulière
  Rémi Duraffort
  Jakob Leben
  Jean-Baptiste Kempf
  Jean-Paul Saman
  Jean-Philippe Grimaldi
  Jean-François Massol
  Gaël Hendryckx
  Jakob Leben
  Jean-Marc Dressler
  Jai Menon
  Johan Bilien
  Johann Ransay
  Joris van Rooij
  JP Dinger
  Jean-Philippe André
  Adrien Grand
  Juha Jeronen
  Juho Vähä-Herttua
  Kaarlo Raiha
  Kaarlo Raiha
  Kamil Baldyga
  Keary Griffin
  Ken Self
  KO Myung-Hun
  Pierre Ynard
  Filippo Carone
  Loïc Minier
  Luca Barbato
  Lucas C. Villa Real
  Lukas Durfina
  Adrien Maglo
  Marc Ariberti
  Mark Lee
  Mark Moriarty
  Martin Storsjö
  Christophe Massiot
  Michel Kaempf
  Marian Ďurkovič
  Mirsal Ennaime
  Carlo Calabrò
  Damien Lucas
  Naohiro Koriyama
  Basos G
  Pierre Baillet
  Vincent Penquerc'h
  Olivier Aubert
  Pankaj Yadav
  Paul Corke
  Pierre d'Herbemont
  Philippe Morin
  Antoine Lejeune
  Michael Ploujnikov
  Jean-Marc Dressler
  Michael Hanselmann
  Rafaël Carré
  Ramiro Polla
  Rémi Denis-Courmont
  Renaud Dartus
  Richard Shepherd
  Faustino Osuna
  Arnaud Vallat
  Rob Jonson
  Robert Jedrzejczyk
  Steve Lhomme
  Rocky Bernstein
  Romain Goyet
  Rov Juvano
  Sam Hocevar
  Martin T. H. Sandsmark
  Sebastian Birk
  Sébastien Escudier
  Vincent Seguin
  Fabio Ritrovato
  Sigmund Augdal Helberg
  Casian Andrei
  Srikanth Raju
  Hannes Domani
  Stéphane Borel
  Stephan Krempel
  Stephan Assmus
  Tony Castley
  Pavlov Konstantin
  Eric Petit
  Tanguy Krotoff
  Dennis van Amerongen
  Michel Lespinasse
  Can Wu
  Xavier Marchesini
  Sébastien Toque
  Christophe Mutricy
  Yoann Peronneau
  Yohann Martineau
  Yuval Tze
  Scott Caudle
  Clément Stenac

It is possible, that some minor piece of code was badly tracked, for
some reasons (SVN, mainly) or that some small developers did not answer.
However, as an "œuvre collective", defined as in "CPI 113-2 alinéa 3",
and seeing "Cour. Cass. 17 Mai 1978", and seeing that the editor and
the very vast majority of developers have agreed (> 99.99% of the code,
> 99% of developers), we are fine here.

Missing a "Lesser" in the legal part

This is the POSIX linear congruential pseudo-random generator with
48-bits of state. It is non-secure/reproducible and thread-safe.
rand() is not thread-safe and *ahem* must not be used in VLC code.
rand_r() is thread-safe but obsoleted in POSIX.2008.

For secure random numbers, use the slower vlc_rand_bytes().
vlc_rand_bytes() can also be used to generate the seed if you are short
on idea for a 48-bits pseudo-random value.

avcodec is used from at least three different plugins: avcodec,
switcher (which seems dead though) and indirectly in avformat. We need
to have a common interlock for all of these.

(da big courmischage)

* commands/cmd_fullscreen.*, parser/interpreter.cpp: added a
  "vlc.fullscreen()" command

  win32, by ipkiss and myself...
 Among the features:
 - framework rewritten from scratch, heavily based on design patterns
  => new controls can be (hopefully) created more easily, portability
  to other OS is better, and the interface is less dependant from
  the vlc core
 - new concept of "layout", to provide a window with several different
  views (as in winamp3 skins)
 - controls can now be placed at a relative position to the edges of
  a window, which allow controls and layouts to be resizable (e.g
  for the playlist window)
 - Use of libpng and libfreetype2 for better portability between x11 and
   win32 => ttf fonts and antialiasing
 - New DTD for the xml theme ( *it will probably change again* )
 - Very very beginning of scripting in the xml file
 - And many things I miss
 - And probably many bugs ;)

some cleanup.