[FIX+IMP] account_tax_balance:

* Tests
* PEP8
* Use invoice._convert_to_write(invoice._cache). This way, the onchange will be inheritable and will add here also the added values
* better get_context_values
* unify method compute_balance
* open move lines linked to balance

account_tax_balance/README.rst

@@ -12,7 +12,7 @@ It depends on date_range module and exposes 'compute' methods that can be called
 Usage
 =====
 
-Accounting --> Reporting --> Open Tax Balances
+Accounting --> Reporting --> Taxes Balance
 
 Select the company, the date range, the target moves and 'open taxes'
 
@@ -42,6 +42,7 @@ Contributors
 ------------
 
 * Lorenzo Battistini <lorenzo.battistini@agilebg.com>
+* Giovanni Capalbo <giovanni@therp.nl>
 
 Maintainer
 ----------