Resolve item sets via ClassicAPI; drop Reliquary dependency

Item-set membership and set info now read ItemSet.dbc directly through
ClassicAPI instead of the nampower/Reliquary glue, so set features no
longer require the Reliquary DLL to be installed.

- ClassicAPI.lua: add GetItemSetIDByID and GetItemSetInfo wrappers.
- Utility.lua: repoint ResolveSetItems, CountEquippedSetItemsBySetId,
  GetEquippedItemSetInfo, and GetEquippedSetPieceCount at the ClassicAPI
  accessors. Set-name matching now uses the DBC name (localized; identical
  to the old enUS path on English clients).
- NampowerAPI.lua: remove the now-unused GetItemSet/GetItemSetId/
  GetItemSetItems/GetItemSetBonuses, the dead GetSpellEffectRadius (no
  callers, only radius source was Reliquary), and the orphaned RQ_SafeCall.
- Init.lua: drop hasReliquary detection and its startup feature line.
- Conditionals.lua: update the [set:] comment (no longer Reliquary-gated).

ClassicAPI.lua

@@ -137,6 +137,24 @@ function API.GetInventoryItemID(unit, slot)
     return GetInventoryItemID(unit, slot)
 end
 
+--------------------------------------------------------------------------------
+-- Item Set
+--------------------------------------------------------------------------------
+
+-- ItemSet.dbc ID that `itemID` belongs to, or nil if it isn't part of a set
+-- (or isn't cached yet). Reads the item's m_itemSet field directly -- no
+-- Reliquary, no per-set ItemID[] scan.
+function API.GetItemSetIDByID(itemID)
+    return C_Item.GetItemSetIDByID(itemID)
+end
+
+-- Table describing an ItemSet.dbc row, or nil if `setID` doesn't resolve:
+--   { setID, name (localized), requiredSkill, requiredSkillRank,
+--     items = { itemID, ... }, bonuses = { { spellID, threshold }, ... } }
+function API.GetItemSetInfo(setID)
+    return C_Item.GetItemSetInfo(setID)
+end
+
 --------------------------------------------------------------------------------
 -- Spell
 --------------------------------------------------------------------------------