[impdev] Important note for those who use git

[Aleric Inglewood]

Hi everyone, developers, testers and everyone else who uses git to get
imprudence.

Now that http://redmine.imprudenceviewer.org/issues/670 has landed in
imprudence/weekly
you all should execute the following commands in order to clean up your trees.

You only have to do this once: from now on it will clean up
automatically. If you already did
this (because I told you so on IRC) then you probably don't have to do it again.
It doesn't matter on which branch you do this; however-- if you still
have branches laying
around*) that don't have this patch then you probably should update those first.
New users that start with a fresh clone in the future will never have
to do this (anymore!)

* From inside the linden/ folder/directory, run:

scripts/install.py --uninstall

This cleans out old junk in installed.xml and removes any old stuff still
laying around in libraries/, but (unfortunately) also, possibly, elsewhere.

* Then, to be sure there isn't anything left that wasn't in installed.xml,
remove the whole libraries folder/directory, for example on linux:

rm -rf libraries

Then reconfigure and build as usual (provided you are in a branch that was
merged with imprudence/weekly !).

===================================================================

On a second note, I'd like to draw attention to the following:

If you build the viewer, libraries are installed in .../packaged/lib/*
(lib32 and lib64 on linux 64bit)
If subsequently you switch to a branch that changes install.xml,
changing the version
of one or more libraries, then that does NOT clean up your
packaged/lib folder! In some
cases this is a problem since that folder ends up in LD_LIBRARY_PATH
and libraries (still)
in it are considered for linking during runtime.

So, a heads up: If you switch between branches that change install.xml
you really
should clean out packaged/lib* every time, in order to be sure that
you won't run
into some obscure "bug" caused by mismatching library versions that nobody will
be able to find.