Compas-cem

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**Added**

- Added spiral staircase ghpython example.
- Added Jenssen tensegrity ghpython example.
- Added tube bridge 3d ghpython example.
- Added bridge 2d ghpython example.
- Added dome ghpython example.
- Implemented `TopologyDiagram.is_node_support()`.
- Renamed node and edge key search GH components.
- Implemented `compas_cem.data.Data`.
- Implemented `compas_cem.plotters.TopologyArtist`.
- Implemented `compas_cem.plotters.FormArtist`.
- Implemented `compas_cem.optimization.Parameter`.
- Added artists registration for plotters and grasshopper via `compas.plugins.plugin`.

**Changed**

- Changed reaction force global color from dark blue to dark gray.
- Changed data serialization mechanism to comply with `compas.data.Data`.

**Fixed**

- Fixed bug in auxiliary trails coloring in `compas_cem.plotters`.

**Deprecated**

- Deprecated `TopologyPlotter`.
- Deprecated `FormPlotter`.

**Removed**

- Removed `compas_cem.optimization.serialization.Serializable`.
- Removed `compas_cem.ghpython.components.Node` component.

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**Added**

**Changed**

**Fixed**

* Pinned COMPAS dependency to version 1.8.1 due to NetworkPlotter deprecation.

**Deprecated**

**Removed**

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**Added**

**Changed**

* Changed reaction forces display color from dark green to dark gray.
* Changed loads display color from light green to dark green.

**Fixed**

* Trail-building was ignored assembling deviation-only topology diagrams in ghplugin.
* Fixed bug: Wrapped `EdgeSearch` tuple output in a list in ghplugin.

**Deprecated**

**Removed**

* Removed support for gradient-free NLopt optimization algorithms.
* Dropped "LD" subscript to identify NLopt optimization algorithms.

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**Added**

* Added check to skip adding None objects to `AssembleTopologyDiagram` in ghplugin.

**Changed**

**Fixed**

**Deprecated**

**Removed**

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**Added**

* Added `draw_arrows` argument to `TopologyPlotter._draw_loads()`
* Implemented `TopologyPlotter._draw_load_arrows()` to display loads as arrows.
* Added import/export diagram from JSON to ghplugin.
* Implemented `TopologyArtist.draw_trails()`.
* `TopologyArtistComponent` in ghplugin can draw trails.
* Added `TopologyDiagram.number_of_trail_edges()` and `TopologyDiagram.number_of_deviation_edges()`.
* Implemented `__repr__()` method in diagrams, elements, supports, loads, parameters, constraints and optimizer.

**Changed**

* Renamed edge to edge_key and node to node_key in ghplugin components.
* Changed display color of loads from green to light green.
* Replaced `NodeResults` wit `SupportNodeResults` component in ghplugin.

**Fixed**

**Deprecated**

**Removed**

* Removed `build_trails` component from gh plugin. Merged with `AssembleTopologyDiagram`.
* Removed user access to specify auxiliary trails directions and lengths in ghplugin.
* Removed `nodes` from input to `TopologyDiagram` in ghplugin.

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**Added**

* Added `Optimizer.gradient` and `Optimizer.gradient_norm` as attributes.

**Changed**

* Exposed `eta` and `tmax` in the signature of `Optimizer.solve_nlopt()` instead of hard-coded values.
* Updated ghcomponent `ConstrainedFormFinding` to include `eta` and `tmax` as extra inputs.

**Fixed**

* Converted `Frame` returned by `RhinoPlane.to_compas()` to `Plane` for compatibility of `PlaneConstraint()` in ghplugin.
* Renamed input of ghcomponent `FormFinding` from `eps_min` to `eta`.
* Fixed bug in trail force sign calculation in `equilibrium_state` and in `equilibrium_state_numpy`.

**Deprecated**

**Removed**