Add the fmt library (#4065)

* Replaces AppendVPrintf with fmt::sprintf
* fmt::ArgList now used as a type safe alternative to varargs.
* Removed SIZE_T_FMT compatibility macros. fmt::sprintf is fully portable and supports %zu.
* Adds FLOG functions to log with fmt's native formatting style.

src/BrewingRecipes.cpp

@@ -55,7 +55,7 @@ void cBrewingRecipes::ReloadRecipes(void)
 		AddRecipeFromLine(ParsingLine, LineNum);
 	}  // while (getline(ParsingLine))
 
-	LOG("Loaded " SIZE_T_FMT " brewing recipes", m_Recipes.size());
+	LOG("Loaded %zu brewing recipes", m_Recipes.size());
 }