Revert "Rename 1.world.txt to 1.world"

This reverts commit 9f8f298eefc633a1da3d361df503d28552002599.
v0.0.2.1

World file is now locally referenced. Means you will not need to change
the path depending on your computer.
v0.0.3

Tidied up some code.
Implemented markers and sensing.
v0.0.4

Added combat and tidied up code.