extras/macosx: add buildbot option to the packaging script, so it no longer fails without window server

This is useless and breaks builds if the script is not used anymore
later on.

macosx/libvlc: slim down package size reducing the number of distributed plugins and running our own set of contribs

extras/macosx: adapt and simplify packaging and creation scripts based on the simple libvlc compilation

extras/macosx: add *.txt to the text files shown on the dmg so they are more easy to open for the ordinary user

extras/macosx: add script to create a disk-image for distribution as well as an apple script to beautify the file icon layout

macosx: remove parts used to create a .pkg installer with packagemaker as this tool is no longer with us

Note that there is nothing wrong with execution on 10.6 if linked against the 10.7 SDK as long as the minimal macosx version is specified correctly

npapi/Makefile.am takes care of it already