[cairo] ask for advice about cairo's user_font

[Adrian Johnson]

James Cloos wrote:
> The font's main object is object 5.  Object 41 is the /ToUnicode reference
> of object 5, object 39 is the /Encoding reference, and object 40 is the
> mapping between the glyph names and their procedures.
> 
> It looks like the only bug is that object 41 lacks an entry for <00>.

Thanks for the analysis. I changed user font PDF output a while ago to 
allow glyph 0 to be used but overlooked the need to update the ToUnicode 
stream as well. I've pushed a fix for this.