deprecate Priority structure, use regular UIKit/AppKit - provided lay…

…out priority instead

bump version to 1.0.0

bump version to 0.2.1

release 0.2.0

release 0.1.0

Fix podspec

several fixes to satisfy pod linter

update podspec for multiplatform support

replace length method with methods specific to constraint relation

fix swapped anchors and add unit test for that