Don't process keypoints near border, because after rotation border points
have contrast gradients with rotation border fill.

1. if a component's variation is a global minimum than it should be a local minimum
2. for the small image with invert and blur, the MSERs number should be 20

This ensures that test data is not dependent on the order the tests are
executed in.

(cherry picked from commit 1245cd17)

(cherry picked from commit 370d1ff2)

This ensures that test data is not dependent on the order the tests are
executed in.

This ensures that test data is not dependent on the order the tests are
executed in.

another attempt to make the MSER test pass. removed possible randomization in parameters from run to run

added reasonable test for MSER (including coverage for http://code.opencv.org/issues/4273, http://code.opencv.org/issues/1723 and http://code.opencv.org/issues/756); also, added some "in-progress" info to the Features2d_Feature2d.no_crash test.

Test accuracy for PR#3829.Fix warning on gcc, comment out INIT_RANDOM_SEED for same result each ran.

to compensate for neon ieee754 non-compliancy.
Also changed the comparison between max valid and calculated distance to
make the error message more accurate (in case curMaxDist == maxDist)

quickly corrected the previous refactoring of features2d: moved from set(SOME_PROP, val) to setSomeProp(val)