Issue #77 Break dependency of icon on angle

src/blackmisc/pq/angle.cpp

@@ -52,7 +52,7 @@ namespace BlackMisc
         CIcon CAngle::toIcon() const
         {
             CIcon i = CIcon::iconByIndex(CIcons::StandardIconArrowMediumNorth16);
-            i.setRotation(*this);
+            i.setRotation(value(CAngleUnit::deg()));
             return i;
         }
 

src/blackmisc/pq/physicalquantity.h

@@ -32,6 +32,7 @@ namespace BlackMisc
 {
     namespace PhysicalQuantities
     {
+        class CAngle;
         class CLength;
         class CPressure;
         class CFrequency;