* Separated `Time` unit into `TimeDelta` and `TimeStamp` + small fixes
Addition and subtruction between `Timestamp`s is not allowed, but any
other `Unit` operation/comparison is. `TimeDelta`s can be
added/subtructed to/form `Timestamp`s.
Deserialization of `Timestamp`:
- `Number` -> interpreted as millis from Epoch
- `Instant` (string representation) -> converted to Timestamp
- `Duration` (string representation) -> interpreted as duration since
Epoch (warn msg is logged)
Deserialization of `TimeDelta` is the same as `Time` was before, with the
diference that when an `Instant` is converted to an timedelta since Epoch
a warning message is logged.
* Unit System v2
- Merged `BoundedPercentage` and `UnboundedPercentage`
- Overrided all operation defined in `Unit` in all subclasses to avoid
as much as possible value classes being boxed in bytecode. If units are used as generics
(hence also functions defined in Unit<T>) they are boxed (as double would if used as generic).
- All units companions now subclass `UnitId`, and can be used as keys
(e.g `Map<UnitId, idk>`), while offering `max` `min` and `zero`
methods.
- Division between the same unit now returns `Percentage`
- Added `Iterable<T>.averageOfUnitOrNull(selector (T) -> <specific unit>)`
- `ifNeg0ThenPos0()` now is optional and not invoked on every
constructor
- Now methods in `Unit<T>` are all abstract, forcing override and avoid
boxing in some cases
- Added `@UnintendedOperation` and `UnitOperationException` for methods
that must be defined but are not intended for use (e.g. `Timestamp` +
`Timestamp`)