[RME] Implementing a new way to declare commands

[acs-l]

Implementing a new way to declare commands (preparatory work for new documentation).

Illustration:

# Command's declaration's illustration
RME::Command::declare({:name => :move_to,
                       :parameters => [
                         {:name        => :id,
                          :description => "Event-to-move's identifier",
                          :type        => RME::Command::ParameterType::PositiveInteger},
                         {:name        => :x,
                          :description => "Targeted x coordinate",
                          :type        => RME::Command::ParameterType::Coordinate},
                         {:name        => :y,
                          :description => "Targeted y coordinate",
                          :type        => RME::Command::ParameterType::Coordinate},
                         {:name        => :ghostly,
                          :description => "Tells whether the event can move through anything or not",
                          :type        => RME::Command::ParameterType::Boolean,
                          :default     => false}
                       ]}) { |id, x, y, ghostly| puts "Moving event n°#{id} to (#{x}, #{y}) (ghostly? #{ghostly})" }


# RME::Command::move_to(11, 27, 32)
=begin
Moving event n°11 to (27, 32) (ghostly? false)
=end

# RME::Command::move_to(0, 10, 11, true)
=begin
Moving event n°0 to (10, 11) (ghostly? true)
=end

# RME::Command::move_to(9, 12)
=begin
Invalid parameter: y (should be a Coordinate of a point in a cartesian coordinate system (i.e.: `x` or `y`)). Actual value is nil (i.e.: not provided). (RuntimeError)
=end

# RME::Command::move_to(-23, 1, 1)
=begin
Invalid parameter: id (should be a Positive integer). Actual value is -23 (RuntimeError)
=end