Note: This is not yet tested.

Also: layout improvements for timings in out.xml

Note: The timings are still buggy:
   1. They are not yet reset in each iteration
   2. The timers should have other names.

Note: The output for valenceDensity, valenceCharges, and allElectronCharges is
      preliminary. It does not look nice in out.xml. The date should be
      collected in the routines to enable a nicer output at a different place.

Also in this commit: Enabled output of program version to out.xml.

Also in this commit: small bug fixes for core states output and
introduction of valenceDensity hierarchy layer in out.xml.

Also in this commit: Improved layout for out.xml output of
total energy contributions.

Note: This commit also introduces formatted output to out.xml.
It is not yet complete and not yet fully used for the small
test output of total energy contributions in this commit.

Note that there are still some known issues:

1. Possibly incorrect data for energy parameters, LOs
2. Incomplete data: electron configuration, comment
3. Not neccessarily explicit data: Bravais matrix

This commit also provides helper routines to write out data into out.xml.
Nothing is tested yet. The routines might be horribly wrong.

Note that there are still bugs.

Note that there are still bugs.

from stden (t) and cdngen (f) to allow calculating starting densities
for atoms without core states.

For very simple test systems fleur can now use the inp.xml file
as an input. Note, however, that the functionality is still
very incomplete. Therefore, preliminary fleur has to be invoked
with -xmlInput to make use of inp.xml.

Besides the feature incompleteness it is expected that there are
still some bugs in loading inp.xml. So far it is
only tested for Si and Fe. For Fe a small deviation from the
reference total energy is observed (0.03 mHtr), the magnetic
moments are off by 0.003. The cause is yet unknown.

This commit introduces the new chkmt.f90. Besides some exceptions this
new routine should yield the same results as the old one. With a runtime
scaling of O(N_atoms) it overcomes the bad O(N_atoms^4) scaling of the
old pendant.

Based on v0.26 hybrid branch