[Feature] directional navigation: Improved best "fallback" match determination by giving primacy to "perpendicular overlap" over "directional distance". Related to #191
 [Feature] Improve selectNextCUorScroll() to better handle pages with 2-D CU layout. Closes #194

 - plus, some related refactoring in mod_directionalNav
 - and, some minor code improvements in mod_CUsMgr
[Data] urlData for international.nytimes.com
[Feature] ignore CUs that are too small