Flexbox ios initial commit

Items now appear, but they should initially shrink and they don't

Add 15-ish tests for flexbox layout

Port reasonable flexbox test set

Fixing issues, adding unit tests

Moved from .tsx to .ts and used our ui/builder.parse

tns-core-modules/utils/utils.d.ts

@@ -28,6 +28,7 @@
         /**
          * Bits that provide the actual measured size.
          */
+        export var MEASURED_HEIGHT_STATE_SHIFT: number;
         export var MEASURED_SIZE_MASK: number;
         export var MEASURED_STATE_MASK: number;
         export var MEASURED_STATE_TOO_SMALL: number;