Most themes should generate in < 1s but allow up to 30 seconds for
network latency when opening a remote file, or for fetching remote
resources (CSS, JS, etc) during a local build.
Fix output file name glitch, writing CSS files to destination folder,
and an issue where the process would evaporate before PDF/PNG generation
could complete.
Remove file-based open methods from resume classes; force clients to use
clean string-based or JSON overloads; fix processing glitch in
validate(); tweak outputs; adjust tests; update CHANGELOG; etc.