Adds playable instruments, IDropped, IHandSelected and IHandDese… (#368)

* Instrument test.

* Midi stuff

* Some more work

* This actually works now!

* update

* Midi Audio works!

* Lots of stuff, and cool interfaces for items

* Update

* Fix a few things

* It just works

* Move textures to another folder, remove placeholder description from instruments

* Fix warning

* Use renderer enum

* Instruments now use DisposeRenderer method, and send MidiEvents as they receive them. Deletes InstrumentSystem whoo.

* Fix incorrect sprite paths

* Instruments take midi file size check into account when enabling/disabling midi playback buttons

* Fix crash when pressing drop on empty hand.

* Use new renderer return values for midi/input

* Xylophones are no longer handheld instruments, fix their sprites.

* Use new API

* Remove nfluidsynth from solution

* Timing information

* Use IGameTiming.CurTime for timestamps instead

Content.Server/GameObjects/Components/GUI/ServerHandsComponent.cs

@@ -145,6 +145,8 @@ namespace Content.Server.GameObjects
                 item.Owner.Transform.LocalPosition = Vector2.Zero;
             }
 
+            _entitySystemManager.GetEntitySystem<InteractionSystem>().HandSelectedInteraction(Owner, item.Owner);
+
             return success;
         }