Add new shop type and enhance existing ones a little

- Shops can now sell skill upgrades without skill point costs (currently available only through special node, not through dialogue)
- Spell shops now show level and spell point cost
- Alchemy shops now show ingredients
- Make use of the constants defined for indexing the shop rects
- Support for arbitrary quantities of items in shops, rather than simply infinite for normal shops and one for magic shops (there's no hook for this yet, though, so it can't be used)

src/scenedit/scen.keydlgs.cpp

@@ -252,7 +252,7 @@ short choose_text(eStrType list, unsigned short cur_choice, cDialog* parent, con
 			strings = *ResMgr::get<StringRsrc>("special-contexts");
 			break;
 		case STRT_SHOP:
-			strings = {"Items", "Mage Spells", "Priest Spells", "Alchemy", "Healing", "Magic Shop: Junk", "Magic Shop: Lousy", "Magic Shop: So-so", "Magic Shop: Good", "Magic Shop: Great"};
+			strings = {"Items", "Mage Spells", "Priest Spells", "Alchemy", "Healing", "Magic Shop: Junk", "Magic Shop: Lousy", "Magic Shop: So-so", "Magic Shop: Good", "Magic Shop: Great", "Skill Shop"};
 			break;
 		case STRT_COST_ADJ:
 			strings = {"Extremely Cheap", "Very Reasonable", "Pretty Average", "Somewhat Pricey", "Expensive", "Exorbitant", "Utterly Ridiculous"};
@@ -660,12 +660,12 @@ static bool edit_spec_enc_value(cDialog& me, std::string item_hit, node_stack_t&
 		else btn = 's';
 	}
 	if(btn == '#') {
-		// TODO: Enumify the shop types
 		switch(eShopType(me["x1b"].getTextAsNum())) {
 			case eShopType::ITEMS: btn = 'i'; break;
 			case eShopType::MAGE: btn = 'A'; break;
 			case eShopType::PRIEST: btn = 'P'; break;
 			case eShopType::ALCHEMY: btn = 'a'; break;
+			case eShopType::SKILLS: btn = 'k'; break;
 		}
 	}
 	short val = me[field].getTextAsNum(), mode = (btn == 'S' || btn == '$') ? 0 : edit_stack.top().mode, store;