neworderofjamie/riscv_ise: FeNN 0.0.3

Small update to the FeNN software. Updates include: You can now use const in Variable types to signify that variables are input only. This slightly improves code generation and is particularly useful when you want to provide a time series input (see ALIF example) Small fix to the exponential approximation Improved NIR importer to allow integration method to be selected Updated all code to reproduce all figures from our latest paper Note that because the FeNN github repository uses sub-modules, downloading the source from here will not result in a working version