Bug#733974: Partial diagnosis.

[ERIIX Blaike]

I can't say I'm entirely happy with my result so far, but I have
figured out the general thrust of this bug.  Minetest seems
incompatible with the libjsoncpp in Debian.  Solving this issue
properly may be a mess, but the proof for the location of the problem
also suggests a temporary workaround.

If you have the Minetest source available (Upstream source --
"git://github.com/minetest/minetest"), it contains "src/json/".  From
within, you can simply "g++ -shared jsoncpp.cpp -o libjsoncpp.so.0"
and use LD_LIBRARY_PATH to force the current Debian package to load
that preferentially to the system-wide version.  Suddenly, the server
list and online mod repo work as they do upstream.

An obvious temporary solution is to keep the bundled libjsoncpp, but a
long-term solution will require figuring out why the system libjsoncpp
fails and either making it work correctly or making Minetest use it
correctly, dependent on which is behaving improperly.

I haven't looked too deeply into which is responsible, though I'd
suspect Minetest.  I'll look into it later, but it is quite late right
now, so I figured I'd send in what I have and get to bed.