Base: Move App::Color to Base

Every basic data type is stored in Base module, color is standing out as
one that does not. Moving it to Base opens possibilities to integrate it
better with the rest of FreeCAD.

src/Mod/TechDraw/App/LineFormat.cpp

@@ -72,7 +72,7 @@ void LineFormat::setCurrentLineFormat(LineFormat& newFormat)
 
 LineFormat::LineFormat(const int style,
                        const double weight,
-                       const App::Color& color,
+                       const Base::Color& color,
                        const bool visible) :
     m_style(style),
     m_weight(weight),
@@ -104,7 +104,7 @@ double LineFormat::getDefEdgeWidth()
     return TechDraw::LineGroup::getDefaultWidth("Graphic");
 }
 
-App::Color LineFormat::getDefEdgeColor()
+Base::Color LineFormat::getDefEdgeColor()
 {
     return Preferences::normalColor();
 }