backport commit 659ffadd

Found via `codespell -q 3 -S ./3rdparty,./modules -L amin,ang,atleast,dof,endwhile,hist,uint`

backporting of commit: 32aba5e6

Merge two Haar Cascade tutorials (#14674)

* move haar cascade introduction, add code explanation, mark content as moved

* switch to ref for include to provide correct breadcrumb navigation

Also fixed some typos and code alignment
Also adapted tutorial CPP samples
Fixed some identation problems

corrected constants,  changed objdetection.cpp as well

updated objDetection2.cpp as well

fixed headers in objdetection2.cpp

removed useles RNG

fixed buildbot warnings (wow, i like that bot!)

victim of the war on whitespace

fixing buildbot warnings

fixing last buildbot warning, heya .

trying to rebase/squash commits

Also move cv::linemod to own header

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

These codes should be included into regular builds.