Added sections to gallery of examples

Modified travis_script.sh to account for the new structure of the gallery

Added README.txt files in directories of gallery examples

Fixed references to gallery images in user guide pages

Fixed broken links

doc/examples/features_detection/plot_corner.py

@@ -0,0 +1,37 @@
+"""
+================
+Corner detection
+================
+
+Detect corner points using the Harris corner detector and determine subpixel
+position of corners.
+
+.. [1] http://en.wikipedia.org/wiki/Corner_detection
+.. [2] http://en.wikipedia.org/wiki/Interest_point_detection
+
+"""
+from matplotlib import pyplot as plt
+
+from skimage import data
+from skimage.feature import corner_harris, corner_subpix, corner_peaks
+from skimage.transform import warp, AffineTransform
+from skimage.draw import ellipse
+
+
+tform = AffineTransform(scale=(1.3, 1.1), rotation=1, shear=0.7,
+                        translation=(210, 50))
+image = warp(data.checkerboard(), tform.inverse, output_shape=(350, 350))
+rr, cc = ellipse(310, 175, 10, 100)
+image[rr, cc] = 1
+image[180:230, 10:60] = 1
+image[230:280, 60:110] = 1
+
+coords = corner_peaks(corner_harris(image), min_distance=5)
+coords_subpix = corner_subpix(image, coords, window_size=13)
+
+fig, ax = plt.subplots()
+ax.imshow(image, interpolation='nearest', cmap=plt.cm.gray)
+ax.plot(coords[:, 1], coords[:, 0], '.b', markersize=3)
+ax.plot(coords_subpix[:, 1], coords_subpix[:, 0], '+r', markersize=15)
+ax.axis((0, 350, 350, 0))
+plt.show()