* [designspaceLib] WIP: add conditionSets to RuleDescriptor...
the BaseDocReader still needs to be updated to be able to read both
legacy condition-without-conditionset and new-style conditionset
elements.
* test_rules: replace rule.conditions with conditionSets
* Tests: update test.designspace to use conditionset; replace 'with' with 'byname' in sub element
I don't like too much that now 'byname' precedes alphabetically 'name'.
We need to see if ElementTree allows to sort attribute arbitrarily
* Change versionnumber to 4.0 - would that be enough, or should there be seperate major / minor fields?
If we bump the version up to numeral 4, I'd like the check for the with / byname attributes. We can read the old `byname` and only write the new `with`.
Remove support for `initial` in axis attributes.
* WIP - formatversion, with attribute,
* WIP
anything that is not version 4.0 is version 3.0
added some local paths to the test so I can see what it's generating. I can take this out later.
* WIP
read the conditionsets properly. This makes the tests fail no longer.
* WIP
disambiguate axis tags from axis names. Test axes are now called "axisName_x", tags are called "TAGX"
* WIP forgot to push
* WIP
Raise `DesignSpaceDocumentError` when no maximum or minimum are given in a condition.
Add test for such an incomplete rule.
Remove path cruft.
* WIP improved test of raised error.
* WIP because no bot.
* WIP more spaces around percents.
* WIP - don't skip empty subs, just load whatever is there.
* WIP do not permit empty axes in a location when evaluating a rule. Fix some tests.
* WIP missed a str(tempdir), some rule tests.
* WIP proposal for changes to the designspace spec to the `rule` and `sub` elements.
* WIP edits.
* WIP. Typo.
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.
