Add support of creating objects in code blocks

[rlc2]

Add support of creating objects in code blocks

[rlc2]

Added in commit aad03e6.
Find the action name in pygame_maker/actions/action.py inside an ACTION_DATA_YAML dict; the order and number of parameters following the action's name should be supplied as arguments to the function.
Therefore, to call create_object_with_velocity() from user code:

ACTION_DATA_YAML = """
...
    create_object_with_velocity:
      - object: common_object
      - position.x: common_position
      - position.y: common_position
      - speed: common_speed
      - direction:
            type: float
            default: 0.0
      - child_instance:
            type: bool
            default: False
      - relative: common_relative
...
"""

The above excerpt shows the arguments needed:

1. object is a string naming an object type
2. position.x is an integer X coordinate
3. position.y is an integer Y coordinate
4. speed is a decimal number for the object's movement speed
5. direction is a decimal number for the direction of motion in degrees
6. child_instance if true, means create the new object as a child of the current object
7. relative if true, means interpret position, speed, direction as relative to the current object
   The "current object" refers to the object instance that executed the code block.
   Remember that the language parser won't recognize bare function calls, so you need to use it in an assignment, E.G.:

ok = create_object_with_velocity('obj_UFO', 20+randint(screen_width-40), 0, 1.0, 180.0, false, false)

This should create an instance of obj_UFO at the top of the screen that moves downward at 1 pixel per frame. The variable ok will equal 1 if the action was successfully called, 0 otherwise (these can also be compared with booleans true and false).