- set the GError when dailing to load a curve map/SPS data
- fixed using wrong module function name when deciding what Cairo surface to create
- fixed drawing the wrong selection objects for some graph selection modes
- handle units of completely empty curves by returning formats for [0,1] in
- renamed skew to skewness in visible labels and public function names
- use gwy_derive_units() to derive result units
- fixed trying to apply mask combination from settings even when there is currently no mask
- changed Invert height checkbox to Mark valleys as it did not make sense with absolute