Add sym/cmp for coax/triax connectors

[eto-]

SUMMARY

Added spacers category (should go in base?).
Added symbols and components for spacers and coax/triax conectors

DATASHEETS / REFERENCES

OPEN QUESTIONS / UNRESOLVED ISSUES

Spacers cat should go in base?

CHECKLIST

• I have read and followed the library conventions¹.
• For packages, I followed IPC7351C (see details in library conventions).
• For modified elements, I bumped their version number².
• I already used the new library elements in a design and verified their correctness (optional).
• I'm the copyright owner of the added content (i.e. the changes are made by myself, not copied/imported from somewhere else).
• I agree to publish all my changes under the CC0 Public Domain License³, allowing everyone to use and modify the content without any restrictions.

¹ Library Conventions: https://docs.librepcb.org/#libraryconventions
² Minor version bump if only metadata was modified (e.g. "0.1" -> "0.1.1"), major version bump if functional changes were made (e.g. "0.1" -> "0.2")
³ CC0 Public Domain License: https://en.wikipedia.org/wiki/CC0

[ubruhin]

I'm not sure about the spacer - it seems to have an electrical signal, but I'd expect spacers to have no electrical function. Also categories should go to the base library. For now, I just removed them to get this PR ready.

The connectors look nice, I just added a few minor changes. I also renamed the component signals and prefix (don't know where the terms "C", "H", "G" and "CN" come from, please let me know if there's a reason to keep these names).

[eto-]

Spacers are both a mechanical tool and an electronic connection.
When you have board with mezzanines the ground is typically delivered by these conductive spacers.
The spacers can be implemented with screws or with specific SMD components. Just as an example the M.2 standard (used by SSD and in IoT for micromod) uses SMD spacers.
Since LibrePCB generates the 3D modeling the spacers will be useful, therefore the need for the symbol.

For the triax the previous name were C = cold, H = hot, G = guard. The other standard is Force, Shield and Guard.

[ubruhin]

The spacers can be implemented with screws or with specific SMD components. Just as an example the M.2 standard (used by SSD and in IoT for micromod) uses SMD spacers.

Ah now I understand what you mean. It seems on Digikey they are called "standoff". Anyway, I'd say that should go to the base library, not connectors. And I'd try to draw a more expressive symbol (maybe check first how it is drawn in other EDA tool libraries). And no new category is needed, there's already "Electromechanical -> Board Spacers".

For the triax the previous name were C = cold, H = hot, G = guard. The other standard is Force, Shield and Guard.

Oops good to know, seems I was a bit too fast with merging 🤦 Renamed it to Force/Guard/Shield in 58e0a55.