remove locally defined, unused typedefs

Such typedefs are identified by GCC ≥ 4.8.
Update submodule libs/h5xx

* libs/h5xx d80d048...122ba9f:
  > remove locally defined, but unused typedef
halmd::cache: fix uninitialised class member

GCC 4.8.2 issued the following warning:

In file included from .../test/unit/utility/cache.cpp:32:0:
.../halmd/utility/cache.hpp: In member function ‘void observer::test_method()’:
.../halmd/utility/cache.hpp:141:60: warning: ‘position_cache.halmd::cache<void>::initial_’ may be used uninitialized in this function [-Wmaybe-uninitialized]
         return count_.lock() == c.count_ && initial_ == *c.count_;
random: revise singleton module, add logging output

Before, it was not possible to obtain the RNG seed and to restart a
simulation with a certain seed.

Disable default instantiation of RNGs.

Drop the Lua function seed(). There is no point in shadowing the
function of the C++ module and assigning the same seed for host and GPU
instances (they use different RNG algorithms anyway).
doc: fix indentation in mdsim.particle