* [TD]Add view snapping preferences
* [TD]fix section snapping algo
- snap sections to section normal line.
- snap views to other views in X&Y
* [TD]fix snapping to ProjectionGroups
- section line convention label
- remove superfluous save/restore on changeEvent
- change default scrub count
- add preference for default symbol dir
- add preference for display of section cut line
as discussed here: https://forum.freecadweb.org/viewtopic.php?f=35&t=53680&p=461356#p461349
* change default tolerance scale to 0.8
* the tolerance scale is directly applied, thus it must have non-italic label
* move tolerance scale to "Dimensions" tab
* move Fuzz settings to "Advanced" tab
* move Conventions to General tab since e.g. the projection angle is an important general setting
* add a note for the label font that this is also used for dimensions and that it there only has an effect for new ones
* use more useful step size of 0.1 for some scaling spinboxes
* sort UI fields in the C++ code to avoid doubled or missing entries (there were 2 doubled entries)
* uniform width of all preferences dialogs
* better alignment for the HLR dialog
Avoid to include ui generated header files within other header files but use forward declarations instead. This reduces dependencies between files and compile time considerably
