This function locates the font file (and index) best matching a name and
optional style (italic/bold). A font file will be returned even if a match
isn't found, but it is not necessarily similar to the requested family and
it should not be relied on for font substitution. The aliases "sans"
,
"serif"
, and "mono"
match to the system default sans-serif, serif, and
mono fonts respectively (""
is equivalent to "sans"
).