--User changes

-Add a new dialog for editing QSS stylesheets. Allow for saving, reloading and setting styles as default.
  --Include a dark style with the installation called dark.qss.
  --Also add support for themes such as Fusion.
  --Resize some controls to better fit with the new style.
 -Add an option to specify the number of random embers generated on startup. 1 is the minimum and the default.

--Bug fixes
 -Properly enable/disable thread priority label in final render dialog in response to enable/disable of the OpenCL checkbox.
 -Remove all inline stylesheets.
 -Show xaos spinners with 6 decimal places.

--Code changes
 -Remove redundant comparisons to nullptr, use ! instead;
 -Give some controls valid names instead of the auto generated ones.
 -DoubleSpinBoxTableItemDelegate.h: Add virtual keyword to overridden functions.

Source/Fractorium/QssTextEdit.cpp

@@ -0,0 +1,10 @@
+#include "FractoriumPch.h"
+#include "QssTextEdit.h"
+
+QssTextEdit::QssTextEdit(QWidget* parent) :
+    QTextEdit(parent)
+{
+    setTabStopWidth(fontMetrics().width(QLatin1Char(' '))*4);
+    setAcceptRichText(false);
+    new CssHighlighter(document());
+}