selene v0.3.0

CHANGELOG:

• Added a set_event() function to setup a callback for the SDL events
• Separated the modules in two:
  • Global modules inside the src/modules/ folder
  • And the selene modules in the src/core folder
• Use the selene('title', 'version', 'org') function for easy initialization
  • When initialized through this method, the framework creates a Window and a Renderer
• Moved the audio module from global to the core modules
  • Separated the AudioSystem function in a file
• Created a command based Renderer (OpenGL) in the core modules
  • Renderer is automatically created when initializing with the selene() method
  • Created a RenderBatch2D to easier manipulation of 2D render stuff, it operates on top of the general Renderer