readmanager 1.5.0

Highlights:
- ReadManager.crop(p_from, p_to, p_unit) — MNE-style cropping; no I/O
  at crop time, every later read honours the bounds, tag timestamps
  shift to the cropped window's t=0.
- get_mne_raw(preload=False) returns a real mne.io.BaseRaw subclass
  (LazyOBCIRaw) that defers sample reads until MNE requests them,
  matching mne.io.read_raw_edf(..., preload=False).
- Public accessors FileDataSource.file_path / .n_samples_per_channel().

See CHANGELOG.md for the full set.