create scaling enchantment for Melee Power / Ranged Power

Currently, there are only a few items in the game that grant bonuses to Melee Power or Ranged Power. These items are quite valuable. However, the values on the items are fairly inconsistent. Therefore, I'd like to see a scaling MP/RP enchantment. There are only around 10 items in the game that grant these bonuses, so ideally it should not be too much work to apply the new scaling enchantment retroactively.

Benefits:
* Balance out existing items.
* Offer new options for MP/RP gear in the future.

As for the progression speed, depending on how generous you want to be (and maybe apply some math what's good comparatively).
* Doubleshot progression has +8 at enchantment level 27-30, matching current best options
* Insightful Stunning has +6 at 25-29, and +7 at 30 (slight nerf).
* Insightful Accuracy has +9 at 27-29, and +10 at 30 (slight buff).