- rationalize var_CreateGet*() and config_Get*() usage

...when the lower layer failed (ie TCP or SSL errors)

FIXME FIXME FIXME FIXME: EXPLICIT HACK.
On the one hand, we cannot hold the lock while triggering a callback, as
it causes a deadlock with video-on-top handling. On the other hand, we
have to lock while triggering the callback to:
 1/ make sure video-on-top remains in sync with fullscreen (i.e.
    unlocking creates a race condition if fullscreen is switched on and
    off VERY FAST).
 2/ avoid possible corruption bugs if another thread gets the mutex and
    modifies our data in-between (though it does not seem like it could really
    do much harm in this particular case).

This is obviously contradictory. Correct solutions may include:
 - putting the fullscreen NAND video-on-top logic out of libvlc,
   back into the video output plugins (ugly code duplication...),
 - serializing fullscreen and video-on-top handling properly instead of
   using the fullscreen callback. That's got to be the correct one.

It now checks if a capable "Media Player" is running, not only VLC.

TODO: playlist management

 activex: when linking against the shared lib DLL, it looks like the linker is picking the DLL name from inside the file, rather than the filename itself. in most cases, this is not a problem, as both are usually the same. Unfortunately, since libtool has a bug on cygwin, whereby the ouput name is libvlc.dll.exe rather than libvlc.dll, the wrong name 'libvlc.dll.exe' is used by the linker rather than the corrected filename. Using the import lib libvlc.dll.a instead fixes that problem. the proper fix should probably a patch to libtool

Don't install mozilla plugin in recommended/default settings on windows. The NSIS stuff needs to be backported to 0.8.6 before we release (and tested). Could someone do that please?

Fix searching in tree playlists (doesn't hide a node's children if the children match but the node doesn't). Thanks to zorglub for the fix.

* objects.c: some more vars command stuff

* Added a minimal streaming feature

Sync default options in NSIS installer with recommended preset. I still don't like installing the activex and mozilla plugins by default as they often override other plugins and make it impossible to view videos on some/many websites.