TODO.yeti

- Spectro tool somehow loses the selection upon data switch.  Maybe data
  browser is to blame.
- Modules:
  - implement sparse laplacian data interpolation
  - polynomial leveling with disjoint z0
  - nanoindentation
- Selection on logarithmic graphs doesn't work
- Surf file: units and scales are botched
- Fix copied channel naming (identical)
- Fix enum documentation after rename, write missing
  libprocess: GwyWatershedStateType, Gwy2DCWTWaveletType, GwyDWTDenoiseType,
              GwyTipType
  libgwydgets: GwyGraphStatusType, GwyGraphPointType, GwyGraphLabelPosition
- Check whether we always emit notification when object properties change
- Display whether data are unchanged/modified/new somewhere
- Swap undo levels to disk
- Add some guessing to Rawfile
- Use gtk_paint_* to keep style in widgets.