Made compositional IC plugins ready for being derived from SimulatorAccess.

Removed the geometry_model pointer that was stored as default in interface.cc
Remove an outdated TODO, leave a new one.
Unified the handling of initial conditions to other plugins.

Previously used pointers to geometry_model, adiabatic_conditions and
boundary temperature were removed and replaced by calls to
SimulatorAccess as in all other plugins. This will break user-defined
plugins, which use these pointers.
log number of inner iterations in Stokes preconditioner
update test outputs
Merge pull request #83 from tjhei/solver_statistics

Solver Statistics
Sort the names of plugins.

Sort the names of plugins in the documentation. Upon visual inspection, also fix a number of formulas and text issues found in the manual's description of the various plugins.
Merge pull request #84 from bangerth/sort-model-names-try-2

Sort the names of plugins.
fix test output
make update_parameters.sh script more robust
Merge pull request #88 from tjhei/fix_a_test

fix test output
fix doxygen formatting in header
comment wrapping, doxygen formatting
run astyle
wrap comments again
fix copyright year
Changed an Assert to an AssertThrow.
Merge pull request #86 from gassmoeller/simulator_access_initial_conditions

Simulator access initial conditions
Merge pull request #89 from tjhei/fixes

Code formatting and astyle
Made AdiabaticConditions a plugin architecture as well.

This resulted in changes to some material models since we no
longer can ask whether get_adiabatic_conditions returns a null
pointer (it will never do now), but instead we need to ask whether
the adiabatic conditions are already calculated, which is a function
that every adiabatic conditions plugin must implement.