No warning when exporting filtered RB transformations without cutoff set

[J.D. Laurence-Chasen]

If you File --> Export --> RB transformations, with default settings i.e. 'filtered', but you haven't yet set a recording frequency or filter cut-off, the export will proceed, but all frames for each RB will be NaN. There should probably be a warning/info pop-up if you try to do this.

[Benjamin Knorlein]

fixes #172 : Added an error dialog for the export of Transformation and 3D points in case filtering is set but the framerate and/or cutoff are not specified

→ <<cset 7478577b2fee>>