Added Graphics, fixed indentation and more

1.- Intro
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I fixed the whole indentation, I added graphics and I fixed some bugs. Also, I added a README and a TODO file.
The README file contains detailed explanations on how to run the game and what to do in it.

2.- Details
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Changes in globals.py
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* Changed globals to be used with graphics.
* Added some comments

Changes in map.db
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* Changed some appearance

Changes in map2.db
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* Created new map based on map.db to expand the world and test player death.

Changes in platformer.py
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* Fixed indentation.
* Changed variables to work with the graphics.
* Fixed the bug that happened when player was hit by an enemy (he recieved damage from all enemies while only hitting one).
* Fixed the bug that made the player invincible by adding a death message and exiting the game afterwards.
* Changed the main function so know it uses graphics instead of rect objects.
* Added argparser to make map selection possible.

Changes in README.md
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* Created it and wrote a project description, installation instructions, dependencies and some other stuff.

Changes in sprites.py
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* Fixed indentation.
* Made all necessary changes to make graphics possible.

Changes in TODO.md
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* Created it and added some ideas.

Changes in world.py
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* Fixed indentation.