Add Dragonriding Vigor module

This displays the Vigor charges for the player whenever they're on a Dragonriding mount (which is detected via explicit buff ID scanning from a hardcoded list...I'd like to make that more robust so I don't have to keep up with new mounts being added, but I'm not sure how to do it another way just yet). The Alternate Power bar is hidden if the Vigor module is enabled so that we don't end up with duplicate Vigor trackers (although right now it flashes on the screen before the mount buff is detected, so I'd also like to fix that...).

I've effectively had to implement my own Vigor module from scratch by poking into the internals of the Vigor widget by its ID in order to determine the recharge amount on the final Vigor charge because there's currently no API to get this information otherwise. Hopefully this gets added; if it does, I'll happily rip out this widget inspection junk. Aside from the partial charge stuff, this is just a skinned version of an Alternate Power indicator that only shows when the user is on a dragonriding mount. ClassPowerCounter doesn't sound like a particularly appropriate base class for this, but since Vigor is implemented as Alternate Power, it worked out nicely.

IceHUD.toc

@@ -101,6 +101,7 @@ modules\ArcaneCharges.lua
 modules\RollTheBones.lua
 modules\EssencePower.lua
 modules\DruidEnergy.lua
+modules\DragonridingVigor.lua
 
 #@do-not-package@
 IceHUD_Options\Json.lua