adds harris corner demo using inline c
added create() for FeatureDetector and DescriptorExtractor
use nonzero in Cv:More
fix ghost object, and support set/get property
fix set/get property
fix matToCvmat
recover detect, compute for Feature2D to fix cygwin
fix pod (see wiki/lib-Cv-Features2d.pm)
fix pod (see wiki/Features2d) #2