Changes

GraphPanel widget: added context menu items for supporting log scales on
axes (#1299).

Some minor cleaning up.

GraphPanel widget: set the linear/log scale as requested (#1299).
Still need to do much work to ensure that the log scales are actually 
sound.

GraphPanel widget: make sure that a plot gets redrawn when changing
scaling of an axis (#1299).

Some minor cleaning up.

Some minor cleaning up.

GraphPanel widget: keep track of the axis range to optimise and make
sure that it gets reoptimised when changing the scaling of an axis
(#1299).

GraphPanel widget: keep track of the axis range to optimise and make
sure that it gets reoptimised when changing the scaling of an axis
(#1299).

Some minor cleaning up.

Some minor cleaning up.

Some minor cleaning up.

Some minor cleaning up.

Properly use qFuzzyIsNull() and qFuzzyCompare().

Some minor cleaning up.

Don't rely on qFuzzyIsNull() and qFuzzyCompare() anymore.
Indeed, to use qFuzzyIsNull() (or something equivalent using 
qFuzzyCompare()) in GraphPanelPlotScaleDraw::label() resulted in small 
numbers (e.g. 1e-100) to be considered as zero, which is not what we 
want. Similarly, we simplified our SimulationData::isModified() method.

GraphPanel widget: make sure that axis labels are properly formatted
(#1299).
Indeed, our previous implementation would render 1e-80 as 
9.99999999999997e-81…

GraphPanel widget: make sure that axis labels are properly formatted
(#1299).
Indeed, our previous implementation would render 1e-80 as 
9.99999999999997e-81…

GraphPanel widget: keep track of the axis range to optimise and make
sure that it gets reoptimised when changing the scaling of an axis
(#1299).

Some minor cleaning up.

GraphPanel widget: make sure that axes are updated if necessary.
This actually fixes a small issue when having, for example, two graph 
panels and asking for the Y axis of them to be synchronised. Indeed, the
Y axes didn’t get synchronised until we panned one of the graphs
(for example).

GraphPanel widget: make sure that axes' alignments are kept when adding
a new graph panel.

Slight updates to our Downloads and What is new pages.

GraphPanel widget: reordered our context menu (#1299).

GraphPanel widget: reset axes when enabling/disabling logarithmic axes
(#1299).

GraphPanel widget: slight improvements to our
GraphPanelPlotWidget::setAxes() method.

GraphPanel widget: some minor cleaning up.

GraphPanel widget: reset our axes when enabling/disabling logarithmic
axes (#1299).

GraphPanel widget: optimise our log axes (#1299).

GraphPanel widget: added a way to set/get the logarithmic state of an
axis (#1299).

GraphPanel widget: export to SED-ML whether a graph panel should have
logarithmic axes (#1299).

GraphPanel widget: support SED-ML files with curves that have a log
scale (#1299).

Some minor cleaning up.

GraphPanel widget: make use of the log scale information found in a
SED-ML file (#1299).

Updated our Downloads and What is New pages (#1299).

Some minor cleaning up (#1299).