Changes

Some minor cleaning up.
 (commit: 4810438)

Some minor cleaning up.
 (commit: d08bc22)

PropertyEditor widget: reorganisation, simplification and cleaning up
of code.
 (commit: 3d6e6c6)

SED-ML support: consider `fatal` errors as errors indeed (!!).
 (commit: 5fedd7c)

Some minor cleaning up.
 (commit: 40c8ee8)

GraphPanel widget: provide a better cap and join style for the pen of a
graph.
Using the default cap and join styles, to increase to the width of the 
pen resulted in rather ugly rendering while it now looks smooth, which 
will be useful when supporting the customisation of graphs.
 (commit: 1e323ba)

GraphPanel widget: small fix to GraphPanelPlotWidget::optimiseAxis().
The problem was that if you have a graph with a log scale and some 
negative data, then to keep pressing F9 might result in the list of 
ticks being empty…
 (commit: e56f01d)

SimulationExperiment view: properly handle fatal/error SED-ML/COMBINE
issues.
 (commit: 2d8510d)

Some minor cleaning up.
 (commit: a5c07f2)

SimulationExperiment view: make sure that a solver's properties are
properly exported to SED-ML.
The problem was with double values. For example, 1e-07 used to be 
exported as 9.9999999999999995e-08. Read back, the value was correctly 
set to 1e-07, so everything was kind of fine except for the fact that 
the SED-ML file gave the ‘wrong’ impression.
 (commit: e82190e)

Some minor cleaning up.
 (commit: ef34e33)

SimulationExperiment view: now have two signals for letting people that
a graph or several graphs have been updated.
 (commit: 9f31338)

Some minor cleaning up.
 (commit: 9e2acfe)