Waveform Simulation: improve selector

[tomcl]

User feedback shows that waveform selector is confusing for large designs.

Improve selector UI as follows:

• Add Focus
• Add breadcrumbs (from focussed sheet to root of simulation)
• Position movement to subsheet next to corresponding custom component ports

Other changes TBC

[tomcl]

Comment on breadcrumbs.

Suppose you have implemented a breadcrumb path from current sheet to root.

To enhance this to a complete breadcrumb tree is surprisingly easy:

1. The trail becomes a table row
2. Other rows are included to make a table so that the nth column contains all nodes depth n
3. No need to go more than one level deeper than current sheet (but could if wanted)
4. Rows are added so that the parent of each sheet in the current tree is the first non-blank table cell one column to the left of the sheet
5. A button can be added to the default single row of breadcrumbs to expand out / hide the hierarchy.
6. Because we go one level deeper than the current sheet it is possible to explore the entire hierarchy by clicking breadcrumbs

This makes the "breadcrumb + current focussed sheet" idea (I hope) really nice and intuitive - and good as a way to understand the design hierarchy.

Each breadcrumb can be implemented as a Button with a function that dispatches a NavigateSelector message with argument the desired new path from current root to selected sheet.

It would be possible to make the "collapsed" form of the breadcrumbs include all the direct subsheets of the current sheet. Then this could be used to focus a subsheet, it might be more convenient then doing that in the selector though I am not sure. it would have the demerit of taking up vertical space all the time.

Anyway this is a chance for a really nice bit of UI design.

Note for @stmy628 I realise you have some way to go before you get to this!

[tomcl]

Maybe the immediate children when expanded could be printed multiple children per line with a black vertical lines demarcating levels to show they are all the same level? Not sure, but that would also be easy to do using a table.