new method: itemType:getRuneSpellName()

[Zbizu]

Pull Request Prelude

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

Changes Proposed

itemType:getRuneSpellName()

returns:

• (string) spell words when used on named rune
• (string) empty string when used on unnamed rune
• (nil) when the item is not a rune

Issues addressed: It will be necessary for lua item descriptions.

[Zbizu]

anything to correct here?

I have improvements for lua item descriptions code partially ready (~50%).