Currently unused but will be super helpful for optimizing the formats of contextual lookups.
* Splits the rules of a class contextual lookup based on explicit subtable breaks
* Returns various properties on the ruleset to help determine appropriate layout format.
* (More properties, such as "touched glyphs", planned - will be added when needed.)
Refactors feaLib, moving code which builds OpenType lookups into otlLib. Note that this changes feaLib's concept of `location` from a tuple to an object.
Fix for #1985:
* ensure that the AxisNameID in the STAT table is not less than 256. This needed an additional argument to the addMultiLingualName() name table method.
* fvar axis name IDs must also not be less than 256, just like STAT axis names.
