0.5.17: High DPI support, smaller installer, and various other fixes

0.5.17 is a minor release that focuses on integrating HighDPI support into OSC's various subsystems. Various engine assets and model meshes were also removed, compressed, or decimated, roughly halving the size of OSC's installers. Additionally, there's now an easier way to zero coordinates in the coordinates panel (#959), the socket reassignment popup has had a makeover (#957), and various little bugs/regressions were fixed (#958, #952).

Change highlights (see CHANGELOG.md for a full list):

• The 2D backend was updated to support HighDPI scaling (3D is WIP). This means that the [experimental_feature] high_dpi_mode in the configuration is now always true.
• Several (potentially, but unlikely, breaking) changes to the shared geometry/ directory and example models were made. This is to accomodate minimizing the shared geometry directory. Looking forward, model designers should prefer a model-local Geometry/ directory. See CHANGELOG.md for specific changes.
• The Coordinates panel now contains a Pose dropdown that exposes the ability to zero all joint coordinates in the model (thanks @tgeijten, #959).
• The socket reassignment popup was given a makeover, and tries to draw more attention to the Re-Express $COMPONENT in new frame option (thanks @tgeijten, #957).
• The "Frame Definition" workflow is now labelled as deprecated, because we anticipate that it isn't used very much. If you think otherwise, then post a comment on issue #951.
• Fixed a regression where the Display context menu would always be greyed out in the model editor (thanks @tgeijten, #958).
• Fixed 'Wireframe' appearance causing the component's decoration to disappear, rather than showing as a wireframe (#952).