Allow for making more lookups support subtabe breaks. Although AFDKO’s
makeotf supports subtable breaks only in pair pos lookups, I believe
that is an implementation limit that we don’t have to follow; all
OpenType lookups has subtables and it should be possible to code that in
the feature files.
Glyph names matching reserved keywords were not consistently escaped;
they were escaped in GDEF classes but not elsewhere. Call module’s
asFea() function in GlyohName.asFea() to ensure they are consistently
escaped.
When a MarkClassDefinition is inside a block, it gets double indentation
compared to the rest of the block. It should ignore the indent argument
like other similar statements.
ValueRecord had a makeString() method that takes an optional “vertical”
argument, but no code outside the tests sets this argument. Renamed it
to asFea() and dropped the “vertical”, so that it consistent with the
rest of feaLib.ast classes.
If Coverage is None then the subtable is a noop that does nothing and
there is no point in building it. As a bonus, it makes OTS happy since
it will reject subtables where coverageOffset is NULL (0) and the spec
does not say whether this is allowed or not.
ufo2ft feature writer calls feaLib builder with tables=[GSUB] first, to run closure
over glyph substitutions; if the GSUB features contains 'featureNames' blocks, then
an AssertionError will be raised; in this case, we can simply skip building the
FeatureParams tables as we haven't build the name records they point to.
In the IncludedFeaNotFound error, pass on the filename token as
it was included in the include statement, so that a client can do their
thing (e.g. issue a warning to suggest the user to write the path
relative to the UFO itself, instead of relative to the feautures.fea
which is inside a UFO).
Also. resolve includes relative to current working directory when the
IncludingLexer' filename is None because it originates from an in-memory stream.
This would make it easier to construct feaLib AST from code,
where the location is not defined and thus should be None.
Also, we can make other arguments as kwargs with a default
value, now that the first parameter is no longer 'location'.
