Change by-ref passed float or bool parameters to callbacks in public API

* Mostly used for passing a progress float back during a long blocking
  call like opening a capture or doing a copy.
* This is much more feasible for python to bind to.
* In several cases we just use a tiny lambda that updates a float anyway
  since we can't push the progress directly into a progress dialog, but
  need to let it query from a temporary in-between float.

renderdoccmd/renderdoccmd.cpp

@@ -499,7 +499,8 @@ struct RemoteServerCommand : public Command
 
     usingKillSignal = true;
 
-    RENDERDOC_BecomeRemoteServer(host.empty() ? NULL : host.c_str(), port, &killSignal);
+    RENDERDOC_BecomeRemoteServer(host.empty() ? NULL : host.c_str(), port,
+                                 []() { return killSignal; });
 
     std::cerr << std::endl << "Cleaning up from replay hosting." << std::endl;