add effect_range to object of effect class.

[sanslash332]

Add this parameter to the effect class, to indicate the range of, for example a harm effect. In the ability class, with effect_range you set the range that allows to you cast the ability itself, but not the range of the effect. For example, if you want cast a explosion you can set effect_range 6 to indicate that the summoner must be in the square that you want be the center of the effect, but you can't say that you want your explosion have a range of 24 with a harm_level x to affect all objects on that range. A trick that you can do (for now) is the effect turn in to summon x, where x is a unit that have a massive attack with that range and splash damage (and a dekai after the explosion), but you with that can't set a specific target for that damage, like with harm effect. Add this same behavior to effects like heal or something similar.

[soundmud]

I think it's already done. To check the current version clone the repository with Git or download a zip from this URL: https://github.com/soundmud/soundrts/zipball/master