New 'mako' command and module abo.api
API invoice.statement()
Add mako formatters for money and dates
Remove extra newline from 'mako' output
Add 'df' mako date filter (full date)
Improve API for invoice generation
Rename Account.shortname() to short_name()
Add API_Account.bare_name attribute
Fix API_Statement.lines logic

Process movements in reverse order
Add 'mb' (money bare) mako formatter
Add API_Account.statement()

To support mako templates for account statements and mako templates for
invoices with history of previous invoices and payments
Fix 'mako' command to accept any template path
Add compa support for 'mako' command
Add Chart.__contains__() method
API.all_accounts
API_Account.full_name
API_Account.balance_at(date)
API_Account.accounts_receivable
Support non-member invoice generation