Add placeholders for total balance and list of accounts

[zefir-git]

Added several new PlaceholderAPI placeholders.

• %bankaccounts_balance% — the total balance of all of the player’s accounts (ex. 1234)
• %bankaccounts_balance_formatted% — the formatted total balance of the player’s accounts (ex. $1,234)
• %bankaccounts_account_list% — comma-separated list of account IDs owned by the player
• %bankaccounts_account_names% — comma-separated list of account names owned by the player (uses IDs where names not available)
• %bankaccounts_account_count% — number of accounts the player has

Created wiki page: Placeholders

Related: #44