[maze.js] Added Height, Size and some "flags"

**New command :**

/maze.js [block] [width] [length] [height] [size] i2fceavs

- i : adds an entry and an exit
- i2 : places entry and exit in the middle
- f : adds a floor
- c : adds a ceiling
- e : places air blocks
- a : places air blocks only
- v : creates a vertical maze
- s : enables solver

Using only "/maze.js [block]" will still work as before.

**Default values :**

- width : 5
- length : 5
- height (walls height) : 2
- size (cells size) : 1

When using flags, you have to type all the others values before.

**Example :**

- "/maze.js 1 5 5 2 1 i" will work.
- "/maze.js 1 5 5 i" will not work.