Sources + Header Build

Added Source pulling via curl.

scripts/check.sh

@@ -0,0 +1,12 @@
+#/bin/sh
+
+while IFS= read -r url; do \
+[ -z "$url" ] && continue; \
+fname="$(printf '%s' "$url" | sed -E 's/[?#].*$//' | sed -E 's!.*/!!')"; \
+if [ -e "$(OUTDIR)/$fname" ]; then \
+	printf "SKIP: %s (already exists)\n" "$fname"; \
+else \
+	printf "GET: %s -> %s\n" "$url" "$fname"; \
+	curl -o "./sources/$fname" "$url" || { printf "ERROR: failed to download %s\n" "$url"; exit 1; }; \
+fi; \
+done < ${SOURCES_FILE}; \