Fixes #49 (closed). Still pauses a bit when looking for unavailable fonts, but only once per run and font.
Define a macro that's essentially a wrapper around \newfontfamily but loops over multiple candidates, checking each for availability and selecting the first. Suppresses errors from unavailable fonts.
Use macro to create font-family commands for Calibri/Carlito, and KorolevLiU/Calibri/Carlito.
Also load Carlito for pdfLaTeX if available.
$ time make all
...
...
Latexmk: All targets (demo_student_thesis.pdf) are up-to-date
real 0m18.743s
user 0m17.204s
sys 0m1.136s