The following sed command can be used to update TTX sources for the LookupType
change:
$ sed -i'~' 's/<!-- LookupType=\(.\) -->/<LookupType value="\1"\/>/g' *.ttx
Before this change, the compiler would enumerate only the first
glyph class of a kerning pair. However, that behavior did not match
the behavior of the `makeotf` tool.