Release v6.4.0

• [change-log]
• [translations]
• [fix] added validation to match account currency with existing gle and test case
• [fix] remove validation to disallow lower rate
• [minor] removed test case for party multi-currency validation, since party multi-currency is now based on account
• [fix] Only 1 account per company for a party
• Added method get_account_currency
• [fix] Remove party_account_currency from Customer and Supplier, and use currency derived from get_party_account
• [fix] Print 'Attach' field in Stock Entry Detail
• [fix] Apply permissions on address and contact based on permissions of Customer, Supplier
• [cleanup] removed desk_home and desk_home_flows from conf.js
• [fix] [payment-reconciliation] ignore rows with blank invoice numbers
• [enhancement] lower priority for newsletter emails
• [minor] validate invoice number is selected in Payment Reconciliation
• [cleanup] remove backup manager
• [fix] check doc.has_website_permission in order.html
• [fixes] accounts controller add flt
• [fix] return exchange rate as 1 if no account is specified
• [fix] Round status update percentages to 2 decimals
• [fix] In get_bom_items_as_dict don't filter by is_pro_applicable for multi-level bom
• Update get_item_details.py
• [fix] if no party, don't validate due date based on credit days
• [chart-of-accounts] added default for Guatemala
• [optimize] customer outstanding query
• [fix] Fetch gl entries in receivable/payable report only if party mentioned
• [report] Trial Balance for Party