More config options, API Event, anvil cosmetic changes

[NezuShin]

Hello! I've added to plugin few new features that I am needed:

1. New ItemParseEvent needed to change arbitrary data of every item (For example, add new lore lines)
2. Option to disable placeholder processing for lore or name
3. Put message "Placeholders are not allowed!" to config
4. "block-anvil-placeholders-silently" config property - if item's name contains placeholder, will set result item to null in anvil inventory
5. /pim update-inventory sub command for easier placeholders debugging
6. Auto replacement for legacy color codes to minimessage format. Without this fix it is impossible to replace placeholders for items with section sign codes. (§r, §e, §#FFFFFF, etc)

New config properties will not break existing configurations.