List of main changes:
- Interval arithmetic
- Digit grouping.
- Enhanced display of parsed expression.
- Bitcoin support (frequent exchange rate updates are recommended).
- Use 'X' and 'E' (or appropriate Unicode characters), instead of 'A' and 'B', in duodecimal numbers (base 12).
- Option to disable units in physical constants.
- Fixed engineering mode.
- Various bug fixes and minor feature enhancements.
Depends on D1573
Signed-off-by: Pierre-Yves <pyu@riseup.net>