Misc. improvement proposals (don't automerge!)

Please don't blind automerge that into the project. 
While this solves the following problems for me:
 - No prices in management view
 - Not able to left click to enable management mode

... I still have issues I couldn't figure out yet, which may are related to the changes made:
 - Items losing price and instead are saved with "price-lore" as item-lore, cause unknown
 - shift click in some views are not handled, and therefore f*ckup things

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Off-Topic Notes (changes I may start in a new branch):
 - In my opinion every view should have its own class, instead of only be one method in the Stock
 - In my opinion the price calculation should be done within StockItem, which should be passed to ItemAttr.onStatusLoreRequest, so that static call to Price.loreRequest becomes obsolete.