Environment_Engine: Calculation of linear thermal bridging lengths

#### Description:

Compliance calculations for Part L of UK Building Regulations requires the calculation of heat loss through linear thermal bridges. This requires us to measure the lengths of each junction type for our entire analysis model, see example of measurements below:

Historically this has been done manually for domestic Part L1A calculations from 2D PDF markups but as we move towards workflows using 3D geometry for this analysis there is an opportunity to automate the calculation of these thermal bridges. Coincidentally, a requirement to measure these thermal bridges is also due to be introduced in the new version of the non-domestic Part L2 2021 so there is the potential for additional benefit from automation.

It would be good if we could develop a method or series of methods to automatically calculate the lengths of each junction type through geometrical interrogation of the analysis model geometry e.g. check for coincident vertices of Wall/Roof elements and return length.

An addition to this calculation would be the development of a visualisation tool to produce an output similar to the image above to allow for visual inspection and QA that the calculation has been completed correctly. (this should probably be tackled as a separate issue)