A few more minor fixes geared towards lgtm.com alerts (#6127)

* Remove unfilled formatting placeholders in KLT parser.
* Fix presumably unintentionally missing reference on PlanatPtr and ChunkyPtr call operators.
* Fix catching pointer and make use-after-free of workimg easier to spot.
Make sure all of our thrown exceptions derive from std::exception and then catch
by reference instead of by pointer.
* Fix mismatch between array form new and non-array form delete.
* Simplify memory management of embedded color profiles by unifying allocation to use operator new.

rtengine/improccoordinator.cc

@@ -1652,8 +1652,10 @@ void ImProcCoordinator::updatePreviewImage(int todo, bool panningRelatedChange)
 
                 // Computing the internal image for analysis, i.e. conversion from WCS->Output profile
                 delete workimg;
+                workimg = nullptr;
+
                 workimg = ipf.lab2rgb(nprevl, 0, 0, pW, pH, params->icm);
-            } catch (char * str) {
+            } catch (std::exception&) {
                 return;
             }
         }
@@ -1728,6 +1730,7 @@ void ImProcCoordinator::freeAll()
         }
 
         delete workimg;
+        workimg = nullptr;
 
     }