Improve svg rendering of 1D and 2D mesh for ipython notebook.
Add commented out code for using new ufc enabled_coefficients feature.
Some minor refactoring of SystemAssembler and prepare for using new ufc enabled_coefficients feature.
Add more outcommented use of new ufc enabled_coefficients.
Enable use of integral.enabled_coefficients() in all assemblers except
PointIntegralSolver.

bench_fem_assembly_cpp shows no performance regression.
Disable unneccesary call to UFC::update in SystemAssembler.

This caused a segfault after my recent changes, but I already commented
that it has no function so I just removed it instead of fixing the crash.
Bugfix, try to make C++11 initializer list code build on precise.
Merge branch 'martinal/topic-improve-mesh-svg-rendering'
Merge branch 'martinal/topic-add-enabled-coefficients-per-integral'