warn if configured font does not directly cover all glyphs #31
Description
The PRImA converter does not itself provide this, but we could do it externally (prior to conversion):
for every codepoint in the text to be extracted (from textequiv_level), check against the cmap table of the selected font. If a glyph is missing, warn.
We could even provide the ability to merge multiple fonts in order to avoid gaps.
See this Pillow issue for a discussion how this could be achieved.