refactor _stringLocationOffset to property in DTCoreTextLayoutLine
advance glyphRun.stringRange by _line.offstringLocationOffsetset
Add single selector cascade and test
remove renamed method -- left it in accidentally while testing
Merge pull request #564 from amro/add_single_class_cascade

Add single class cascade
Fix substring selectors being matched when cascading
Merge pull request #565 from amro/fix_substring_selector_cascade

Fix substring selectors being matched when cascading
Merge branch 'kybook' into develop
Merge pull request #566 from kolyvan/develop

Fixed glyphRyn has wrong stringRange for hyphenated lines
Fix selector order on the mac
Merge pull request #567 from amro/fix_mac_selector_order

Fix selector order on the mac
use array instead of ordered set
Merge pull request #568 from amro/fix_mac_selector_order

use array instead of ordered set
Add weighted selector specificity and tests
actually assign the sorted array of selectors to something...
Merge pull request #569 from amro/fix_selector_weight

This PR adds selector weights to sort selectors by specificity
Fixed problem with tabStops not getting copied.
Merge pull request #571 from Torsph/develop

Fixed problem with tabStops not getting copied.
improve unit test to check for another edge case re:breaking ties
weight single class selectors based on their distance from the target element since they all have the same specificity value.