Base/App: fix warnings from code analysers:

* convert old-style-casts to explicit C++ casts where possible
* make some implicit conversions explicit

src/Base/FutureWatcherProgress.cpp

@@ -40,7 +40,7 @@ void FutureWatcherProgress::progressValueChanged(int v)
 {
     if (steps == 0)
         return;
-    unsigned int step = (100 * v) / steps;
+    unsigned int step = (100 * static_cast<unsigned int>(v)) / steps;
     if (step > current) {
         current = step;
         seq.next();