Generate tikz_pngs in a more Makefile-y way
addprefix, addsuffix, and list-aware notdir and basename instead of
using foreach.
@@ -4,7 +4,7 @@ generated_img_dir=img/generated
tikz_files := $(filter-out img-src/_%,$(wildcard img-src/*.tikz))
-tikz_pngs := $(foreach file, $(tikz_files), $(generated_img_dir)/$(notdir $(basename $(file))).png)
+tikz_pngs := $(addprefix $(generated_img_dir)/,$(addsuffix .png,$(notdir $(basename $(tikz_files)))))
.PHONY: clean docs pngs
