Add methods to support sequential resource destruction

specter/include/Specter/FontCache.hpp

@@ -191,6 +191,8 @@ public:
     void closeBuiltinFonts() {m_regFace.close(); m_monoFace.close(); m_curvesFace.close();}
 
     const FontAtlas& lookupAtlas(FontTag tag) const;
+
+    void destroyAtlases() {m_cachedAtlases.clear();}
 };
 
 }

specter/include/Specter/ViewResources.hpp

@@ -188,6 +188,11 @@ public:
     ViewResources& operator=(const ViewResources& other) = delete;
     ViewResources& operator=(ViewResources&& other) = default;
 
+    void destroyResData()
+    {
+        m_resData.doDestroy();
+    }
+
     ~ViewResources()
     {
         if (m_fcacheThread.joinable())