The following sed command can be used to update TTX sources for the LookupType
change:
$ sed -i'~' 's/<!-- LookupType=\(.\) -->/<LookupType value="\1"\/>/g' *.ttx
* feaLib: limit language statements to 1 feature block
language exclude_dflt statements should only apply to lookups
defined in their feature block and not to lookups defined
in previous blocks sharing the same feature tag
* feaLib: add BuilderTest::test_FeatureFile_multiple_feature_blocks