Preparation for pull request

Additional cleaning for simplex method, removing the parts that are
currently unused. Removing developer's notes. Trying to reach production
level.
Fix qualifiers on aux functions for solveLP()

Change qualifiers on auxiliary functions (for solveLP() procedure) from
const (that does not have much sense) to static (that makes them
invisible for outside world and hopefully exacerbates optimization).
Fixed the warnings

Fixed the code so to eliminate warnings related to shadowing and unused
parameters. In some settings, these warnings may be treated as an errors
and lead to failed build.

Suggested by Nikita Manovich.
Fixing the warnings

Fixed all of the warnings.
Convenience fixes

Attempting to fix issues pointed out by Vadim Pisarevsky during the pull
request review. In particular, the following things are done:
*) The mechanism of debug info printing is changed and made more
procedure-style than the previous macro-style
*) z in solveLP() is now returned as a column-vector
*) Func parameter of solveLP() is now allowed to be column-vector, in
which case it is understood to be the transpose of what we need
*) Func and Constr now can contain floats, not only doubles (in the
former case the conversion is done via convertTo())
*)different constructor to allocate space for z in solveLP() is used,
making the size of z more explicit (this is just a notation change, not
functional, both constructors are achieving the same goal)
*) (big) mat.hpp and iostream headers are moved to precomp-headers from
optim.hpp
Minor fixes

In request to the comments for the pull request.
Simplify printing procedures

Use opencv's print() procedure in place of my own procedures to output
matrices and std::vectors.

Interestingly enough, operator<< does not work for matrices, when called
from my .cpp files in src/ subfolder of the optim module, although it
works when called from tests and stand-alone programs, compiled with
opencv. I think, this requires investigation and, maybe, bug report.