add TemperatureOrComposition::component_index
start work on DirectSolver by putting u+p into one block

Still incomplete, have to fix many other places that assume specific
blocks. I had to rework Introspection::BlockIndices for this.
rework initial temperature conditions to use component_index
Merge branch 'master' into direct_solver

Conflicts:
	source/simulator/initial_conditions.cc
	source/simulator/introspection.cc
fix merge
fix advection assembly blocks
fix block indices in several places
remove debug output
fix copy&paste bug
fix temperature postprocessor
do not build preconditioner for direct solver
remove debug output
disable pressure normalization for now
disable pressure scaling if using direct solver
Fix visualization output time

The visualization output still uses seconds rather than years even if
the “Use years in output instead of seconds” parameter is true, this
patch should fix it
Minor fixes to last patch
Merge remote-tracking branch 'upstream/master'
Add missing endline.
Merge pull request #6 from bangerth/master

Add a missing newline.
run astyle