Changes to mainWFG, added Kolmogorov & vonKarman

The WFG-for-main was giving unexplainable conflicts with the master. Now
created a new branch from the master and added the files to the new
branch and all seems to work just fine now.
Files should now work correctly, independent on OS, or start path.
Fixed file import in testNollMapping().
Fixed assertion problems.
Implemented Photon and Readout Noise for WFS.
Kolmogorov/von Karman aberrations

-Major update to von Karman/Kolmogorov aberrations: Now includes high
frequency content.
-Fixed a error: A multiplication in the PSD sould have been a addition
-Fixed a error: The grid creation: a minus sign added for the lower
limit

Joao, would you please check if you can agree on the results produced by
the code? I find phases in the range +/-20rad with spikes up to
+/-40rad, but then literature seems to give similar ranges. This might
also give problems in WFR, can their code/approximations handle such
large ranges? We'll see I suppose...
Choose aperture in zernike wavefront

Upon special request of some people: the circular aperture is not
applied automatically now in createWavetront(...), it however still is
present in plotWavefront(...) as a square grid it is mathematically
incorrect. If desired, it can still the applied and removed via the
'circAperture' flag in both function.
Updated noise strengths, fixed photon noise (Poisson)
Spell check and added some comments
Fixed bugs, one for messages when overiding certain values and other the bug in the tilt.
Bug fix for wrong arrangement of arguments.
Merge pull request #83 from faitdivers/WFS_iss57

WFS_iss57 Sensor Noise Implementation
Everything seems ok!
Fixed conflict in mainWFS.py
Merge pull request #85 from faitdivers/WFSBugFix

Fixed bugs in WFS
Solved issues in test file

On request I removed the circular apperture, but retained the old data
set with aperture. Should be fixed now.
Merge pull request #77 from faitdivers/WFGbranch

Changes to mainWFG, added Kolmogorov & vonKarman
changes in the creation of the G matrix; changes in the test procedure for WFR
Merge branch 'master' into iss32
Merge branch 'master' of https://github.com/faitdivers/pyao into iss32
added a Zernike aberration to the test of WFR