Release 1.4.0

What's Changed

• Feature/object picker by @aprotopsaltis in #53
• Feature/ecss graph improvements by @kamarianakis in #52
• Adding more systems by @kamarianakis in #57
• A second example with textures by @kamarianakis in #58
• Feature/ecss decorator2 by @aprotopsaltis in #61
• Add skinning example notebook by @kamarianakis in #60
• Release 1.4.0 by @kamarianakis in #62

Full Changelog: v1.3.0...v1.4.0