Fixed doc for Bug #3887

Clarify how the mask parameter is set on output and how this is
affected by the flags parameter.

resolves Feature #2942

Fixed spelling of CV_INTER_LINEAR flag in geometric_transformations.rst

Cleaned up adaptive bilateral filtering, added support for gaussian interpolation, updated sample and docs

Added extra information for fitEllipse, minAreaRect and addapted ellipse &
ellipse2Poly parameter description.

ReST directive was used. Also fixed some other ReST directives that were
not correct and removed some warnings during buildbot checks.

- Used lunix style slashes - works on most systems
- Removed all trailing whitespaces

The orientation of convexHull's result is currently the opposite of what the
documentation would suggest:

>>> import cv2, numpy as np
>>> points = np.array([[0,0],[0,1],[1,0]], dtype=np.int32)
>>> cv2.convexHull(points, clockwise=False)
array([[[1, 0]],
       [[0, 1]],
       [[0, 0]]], dtype=int32)
>>> cv2.convexHull(points, clockwise=True)
array([[[0, 0]],
       [[0, 1]],
       [[1, 0]]], dtype=int32)

Changing the function itself is probably not a good idea at this point, so
this fixes the documentation by flipping the coordinate system.

I also removed the mention of the origin, since it's irrelevant for this
function.

bug #2709

All errors were found by doc/check_docs2.py

This partly reverts commit 6ca61827.

added synonym CV_COMP_HELLIGNER for CV_COMP_BHATTACHARYAA to reflect the real formula used (bug report #2073)