[SlashEMDS] Shopkeeper Identify service Basic/Premier prompt

[DeMatt]

Shopkeepers in Slash'EM offer additional services (http://nethackwiki.com/wiki/Shopkeeper_services), accessed by attempting to Pay whilst not having any actual bills. While some services are exclusive to a particular type of shopkeeper (e.g. Weapon-works is only available from weapon shops), the "Identify" service is available to all.

Unfortunately, in the current port, Identify (and specifically Identify) does not work:

1. You attempt to pay -> shopkeeper asks if you want to try additional services (Yes/No prompt)
2. Select "Yes" -> shopkeeper lists available services
3. Select "Identify" -> shopkeeper prompts for an item
4. Select an item -> shopkeeper attempts to prompt for "B)asic or P)remier?" service -> program lockup

As other services do not have this specific prompt, (just a Yes/No confirmation at the end) they work.