- there is no reason to hide it and even a bit tiring to open it manually since most no new primitives should be at the origin
- give the combobox to select the primitive type a reasonable name, this helps to understand the code better
- fix bug that custom angles were overwritten
- the norms only define screw heads, not the cut for them, so also a custom angle is possible to sink a metric screw
- use better step in UI since one changes the presets only in fractions of a millimeter (otherwise it would be a different hole size)
- handle case of no cut
- calculate change in diameter when adding depth to countersinks
- propose cut values also for UTS profiles
- the UTS defines coarse and fine while for ISO it is regular and fine, thus fix the name
- for the dialog: set minimum values to zero (angles etc. cannot be negative)
- add definitions for IS 2009, 7046 and 12474
- remove useless file for a ISO 14583 since there are no such screws on the market
- rename "coarse" to "regular" since this what it actually is according to the norms
- uniform the x1 threads (for x2.0 etc we use a trailing zero and for some we use x1, for some already x1.0, thus consistently use x1.0)
- add some ISO 10642 entries
- correct ISO 4762:
- correct some values
- the does does not define a size M27
- add the two missing sizes
Fixes LGTM alert
Per the documentation:
```
A 'pass' statement is only necessary when it is the only statement in a block (the list of statements forming part of a compound statement). This is because the purpose of the 'pass' statement is to allow empty blocks where they would otherwise be syntactically invalid. If the block already contains other statements then the 'pass' statement is unnecessary.
```
- do not use a QSignalMapper if the slot doesn't take care of the emitting widget
- to set the placement only check for the base class GeoFeature, i.e. no need to step through all primitive types
- fix compiler warning of unused variable
- propose valid values for the cut depth and diameter when creating new holes
- add new definitions for metric fine
- some code simplification and comments
