--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/VariationsDialog.ui

@@ -98,7 +98,7 @@
     </widget>
    </item>
    <item row="0" column="0">
-    <layout class="QHBoxLayout" name="horizontalLayout">
+    <layout class="QHBoxLayout" name="VariationsHorizontalLayout">
      <item>
       <widget class="QPushButton" name="SelectAllButton">
        <property name="text">