[+] Make placeholders on upgrade configurable.
[+] Fix auto sell summary message is being sent when it's already disabled.
[+] Now check inventory empty slots when picking up items from collectors.
[+] Add multiplier upgrade (need to see upgrades menu default configuration to implement this, if you're updating from previous version)
[+] Add placeholder {multiplier} on the sell message.
[+] Add default config message for pick up cooldown.