Download and cache FML libs for legacy minecraft versions.

* minor fix for version filtering (1.5 no longer shows forge for 1.5.1 and 1.5.2)
* FML libs are downloaded to mods/minecraftforge/libs and cached
* FML libs are copied to instances which contain FML or forge

logic/LegacyInstance.cpp

@@ -159,6 +159,11 @@ QString LegacyInstance::binDir() const
 	return PathCombine(minecraftRoot(), "bin");
 }
 
+QString LegacyInstance::libDir() const
+{
+	return PathCombine(minecraftRoot(), "lib");
+}
+
 QString LegacyInstance::savesDir() const
 {
 	return PathCombine(minecraftRoot(), "saves");