Implement map loading, player visualization and player movement
through keyboard input.

This reverts commit b791847a.

This reverts commit 10281589.

The Mob class describes a movable object which can move around on
the map. For that to happen we need to know how big the map is and
if we may hit a tile that we should not move on.

The `move_left()`, `move_right()`, `move_top()`, `move_bottom()`
methods need a reference to the map on which the Mob is placed to
check for range and tile.

fix an error in the `build()` method. We need to go through the rows
first and then through each column inside that row.

A world map consists of a N*M matrix. Each entry is a list containing
the following information: [TYPE, STATE, ITEM, ACTION].
TYPE defines the tile type (floor, wall, door),
STATE defines the tiles' state (frozen, deadly, ...).
ITEM defines the item found on that tile,
ACTION defines an action that can be done on that tile.

A map can be stored in a csv file in this format:
TYPE,STATE,ITEM,ACTION

When a field is ommited, it's value is consideres 0:
1,,,   == 1,0,0,0
1,2,3, == 1,2,3,0

The `from_string` and `from_bytes` methods should allow creating a
WorldMap from it's respective formats.