Add `FieldProp` and use it instead of plain `dict`
Do not run `coverge html` in every test
Move constants from class to a module name space and DRY convert methods
Rename `FieldProp` -> `_FieldProp`
Rename `Meta` -> `_Meta`
Privatize
Rename `type` -> `type_`
Use `type_` argument to declare `'long_string'`
Fix `MANIFEST.in`
Rename `to_ascii` -> `__str__` and use `str` to get ascii format
Add `Sac`
Add `test_parse_str`, `test_parse_bytes` and `test_parse_dict`
Add constants `_SQRT2` and `_INV_SQRT2`
Remove `__repr__` and add `__str__`