Fixed inconsistency with flag names

Fixed inconsistency with flag names for solvePnP. 
The default value for the function lacks the CV_ prefix. The code checks against "ITERATIVE". The suggested values for the parameters *include* the prefix.
Even though the enum CV_ITERATIVE (+ CV_P3P, CV_EPNP) = ITERATIVE (& P3P, EPNP), lets show to the users only one of them.
Now the user sees only {ITERATIVE, P3P, EPNP}.
fix typo in linux tutorial
fixed calculation method of "cv::TickMeter"
Merge pull request #2818 from StevenPuttemans:fix_linux_tutorial
Merge pull request #2834 from atinfinity:pullreq/140606-TickMeter-2.4
fixed warnings
Merge pull request #2813 from 23pointsNorth:patch-2
Merge remote-tracking branch 'origin/2.4' into merge-2.4

Conflicts:
	modules/contrib/src/spinimages.cpp
Merge pull request #2838 from ilya-lavrenov:tapi_warnings
Merge pull request #2841 from SpecLad:merge-2.4