Tweaks for Item Rename Framework

[SzwedzikPL]

When merged this pull request will:

• Rename addRenamedItem function to renameInventoryItem
• Add params with typecheck, hasInterface & empty class check & header comment for public use in - renameInventoryItem function
• Make functions & namespace local as @commy2 suggested.
• Rename getInventoryClassname function to getInventoryItemData

Tweak initDisplayInventory function to:

• Make Rename Item Framework work if Item Context Framework options are not present
• Not run if no ItemContextMenuOptions and renamedItems are present
• Not register Item Context Framework event handlers if ItemContextMenuOptions are not present
• Not register Item Rename framework handlers if renamedItems are not present
• Change exitWith to normal if for checking ctrlShown because exitWith will exit whole loop before checking rest of controls