Spatial Design Network Analysis QGIS 4 compatibility

Allows use of the sDNA toolbox from QGIS 3. sDNA version 4.1 or above must be installed first from http://www.cardiff.ac.uk/sdna sDNA is a spatial network analysis tool with general applicability, but particularly suited to modelling urban networks. Standard sDNA currently calculates various measures of network density, gravity models, floating catchment, closeness, betweenness, convex hull and severance statistics. These can be based on different analysis metrics (Angular, Euclidean, Custom). Additional tools allow network preparation, statistical learning and prediction based on sDNA models. Analyses can be weighted or unweighted, and weights can be applied per polyline, link or unit length. An advanced version called sDNA+ is also available which can use arbitrary metrics from a user formula (hybrid metrics) as well as having presets for pedestrian, cyclist and vehicle use, and the ability to output analysis geometries (network radii, geodesics, convex hulls; one-to-one, one-to-many, one-to-all or all-to-all). Version 3.1 adds OD Matrix input and Skim Matrix output. Original development of this plugin was funded by the ESRC Impact Accelerator grant "sDNA for all". The principal investigator was Alain Chiaradia and the co-investigator Crispin Cooper, based at Cardiff University department of Geography and Planning and the Sustainable Places Research Institute. The update to support QGIS 3 was funded by Alain Chiaradia reinvesting revenue from sDNA+. The principal investigator was Crispin Cooper and the software engineer Jeffrey Morgan, based at Cardiff University departments of Geography and Planning, the Sustainable Places Research Institute and Data Innovation Institute.