Release v2.3

• Account settings: added option to set an opening date and balance
• Report: Improved summarily display of categories (1 row/category)
• Bugfix: support non-ASCII characters for payee and category
• Bugfix: fix QIF export of multiple accounts
• Bugfix: don't create a transaction if the user aborted it ("Cancel")
• Rename category type from "Spending" to "Expenses"
• Added French translation, thanks blioberis, Jérôme Duval, and Briseur!
• Update documentation