Adding map layouts and moving obstacles for world 1

[hunghvu]

You have to populate the layout and all objects in worlds 1-1, 1-2, 1-3, and 1-4. Please work on the existed entities first. Throughout the time, new entities may be added. Please consider merging the master branch to yours and update world 1 with new entities.

Update (Mar. 1, 2021): World 1-1 and 1-2 are completed. Do note it's only about map layout, not all entities are implemented. This issue will be keep opened due to in-completed tasks.

[BenjaminDeJager]

most of this level has been done by chris, but the flag and castle still needs to be added.

[hunghvu]

If you think there is not much to be done in this one, then we can update this issue to world 2. Or else, we have to clarify which section of world 1 is still needed to be completed.

[BenjaminDeJager]

I have realized that world 1 =/= level 1

world 1 is the first 4 levels so 1-1, 1-2, 1-3 and 1-4.

chris has (nearly) finished 1-1 but the remaining 3 levels are still valid parts of this issue (we might need to split this issue into seperate ones for each such level btw).