PluginLoad now return an int instead of a bool

Since it's C-exported


Former-commit-id: 77ac90bd7151b086c555ffed50066991910e3cd8

src/Nazara/Core/PluginManager.cpp

@@ -14,7 +14,7 @@
 
 namespace
 {
-	using PluginLoad = bool (*)();
+	using PluginLoad = int (*)();
 	using PluginUnload = void (*)();
 
 	std::list<NzString> s_directories;