Fix StyleParseUtils' splitLength() to support "px" units
Add parameter "epsilon" to core.UnitTestRunner.shouldBe(), for fuzzy number comparison
Add StyleParseUtilsTests
Use absolute tolerance for unit test number comparison

relative tolerance is hard to do with an expected value of 0
Merge pull request #567 from kossebau/fixStyleParseUtilsIgnoringPx

Fix StyleParseUtils ignoring "px" as unit