Dealer Rewrite & Minor Fixes

• Dealer rewritten and somewhat more performant. More importantly it should be closer to the real deal..
• Items() class can now be iterated over to see all items that you have more than 0 of.
• charge_count is now optional and can be randomly generated similarly to the actual game
• When the shotgun is reloaded, it now follows the correct shotgun bullet distribution (Before, the amount of live shells was independent of the total shells; this is incorrect as the amount of live shells = total // 2)
• Meds will no longer allow you to surpass the usual charge count maximum.