Configurable stack size per ItemType

[ArturKnopik]

Pull Request Prelude

• I have followed [proper The Forgotten Server code styling][code].
• I have read and understood the [contribution guidelines][cont] before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

Configurable stack size per ItemType.
Configuration is done in items.xml file by using attribue "stacksize"
Example:

<item id="2316" article="an" name="animate dead rune">
	<attribute key="type" value="rune" />
	<attribute key="runeSpellName" value="adana mort" />
	<attribute key="weight" value="210" />
	<attribute key="charges" value="1" />
	<attribute key="stacksize" value="2" /> <!--  <<< HERE-->
</item>

note: npc now can sell multiple bp's with stackable items.

Issues addressed:
N/A

How to test:
Set 'stacksize' in any stackable item

• Collect items from monsters
• Move items in BP
• Move items to Arrow/Weapon slot
• Buy items from NPC

[ramon-bernardo]

Suggestion

itemType:stackSize(value) // set
itemType:stackSize() // get

[ArturKnopik]

it's used only in shop system
setting stack size should be done only on startup, your change reguest will affect ItemType that is and should be static

[ramon-bernardo]

You're right, I hadn't seen that 😲

[nekiro]

not a fan of this "revscriptsys" way of getters and setters, make it obvious getAnything, setAnything
anything() is confusing and may result in undefined behaviour if you by any chance pass value or actually pass no value, which could happen, because lua is a dynamic language