Add `layerName` attribute to the sourcedescriptor object
Read and write layerName.
Add a source layer test.
XXX this also disables the test_check() test for the moment because it generates odd results.
When an offset refers to a table, we keep the size of the offset to
the referred-to table. When sharing tables, we were ignoring this,
which could result in a long offset being written out as a short, or
vice versa. Fix it by not sharing such tables. This is not optimal
but fixes the bug.
Bug has been there forever.
Takes a template containing predefined strings {dirname}, {basename},
{stem}, {ext} and {fullname}, to customize the location of the binary
master TTFs in relation to the designspace source filenames.
It looks like this was (at least partially) implemented in
f01c86ca9b
Should fix https://github.com/fonttools/fonttools/issues/1237
I'm still not sure about that "File a bug." when AdvWidthMap is None,
but either LsbMap or RsbMap are not None..
And we still need to add tests for this though.
