Misc. typos

+ some are doxy others are just comment code.  
+ some minor whitespace and grammatical tweaks. 
+ app/SCL/* typos have also been submitted upstream (https://github.com/stepcode/stepcode/pull/366). So it's ok to merge them in to master.

src/Mod/Mesh/App/GTSAlgos.cpp

@@ -91,7 +91,7 @@ void GTSAlgos::boolean(const Mesh::MeshObject& ToolMesh, int Type)
   s1 = GTSAlgos::createGTSSurface(_Mesh);
   s2 = GTSAlgos::createGTSSurface(ToolMesh);
 
-  // clear the mesh (mermory)
+  // clear the mesh (memory)
   //Mesh1.clear();
   //Mesh2.clear();