(cherry picked from commit 887736bc)

(cherry picked from commit 1b8c2589)

(cherry picked from commit 3a1bb933)

(cherry picked from commit dfb49097)

(cherry picked from commit d7bb1025)

"int * CvMLData::sample_idx" was not freed

removed invalid condition, it is always false

The implicitly generated ones don't work properly, and I don't want to
write proper ones. :-)

"Fixes" <http://code.opencv.org/issues/3358>.

Looks like we don't actually use them; when creating precompiled headers
with Visual C++, a dummy .cpp is created at build time.

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

weights array is only allocated for (l_count+1) elements,
but then weights[l_count+1] element is accessed.

This should allow many algorithms to take advantage of more parallelization
technologies.

This allows subclasses of CvBoost to override initial weights that
update_weights uses without duplicating its entire implementation.

add hack to disable optimization of linear svms; improved precision of optimize_linear_svm; add the relevant test, which however requires some big database (so it's disabled by default)

Copied the docstring description

Initialize local variables

Also corrected some indexes to be size_t.

Invalid links and refences fixed.
SpaeseMat class documentation updated.