aspects of decimals and integers
For fields and Item's uint8 should be good enough. After
discussions with Alexander Barkov we choose uint16 (for now)
as some format functions may accept +256 digits.
The reason for this patch was to make the usage and storage of decimal
digits simlar. Before this patch decimals was stored/used as uint8,
int and uint. The lengths for numbers where also using a lot of
different types.
Changed most decimal variables and functions to use the new typedef.
squash! af7f09106b6c1dc20ae8c480bff6fd22d266b184
Use decimal_digits_t for all aspects of digits (total, precision
and scale), both for decimals and integers.
