Final cleanup and testing of the user interface

[stfnp]

Required

• When scrolling double inputs (e.g. profie segments) the model should continuously update. Not while typing though, then only when enter is pressed.
• Angle inputs show weird numbers (too many decimals) when set to degrees. Same for arrow mass in grains per pound. Inputs definitely need more rounding and smooth step sizes independent of unit choice.
• When typing the first digit in a new table cell, it is first interpreted as zero and a warning pops up
• 3D View tooltips only show black rectangles on Linux -> Test again on other systems
• Bring back curvature in profile plots, show/hide nodes in all plots, test background image
• Don't color the stress results if permissible stresses are zero?
• Windows: Material color button is grey and not colored like the material.
• Units dialog should not be modal
• Have a look at the InnoSetup warnings
• Tooltip of the color button is colored too
• Individual tooltips for arrow mass definitions
• Individual tooptips "assign material x to this layer" are too much, remove them
• Cancelling the simulation crashes the application
• Set milliseconds as the default time unit

Optional/Later

• Consider making editors persistent like the graphs
• Visualize selection of control points, segments, layers and materials
• Windeployqt: Can the installation be made smaller? Omit language files, for example.
• Result viewer flashes in the top left corner of the screen before opening in the middle