Hack to pass MKL to Armadillo

Otherwise, Armadillo fails to detect out-of-location mkl libraries.
Caching for previously boost unit test flags
Add "" safeguards to TBB lookup recipe
Corrections for boost-lookup

1. BOOST_ROOT, not Boost_ROOT
1. Boost_INCLUDE_DIR needs be specifically undefined, in case an old version of Boost was found
   previously.
1. Same goes Boost_LIBRARY_DIR
Patch boost for intel 13 c++11 :bug:

This is a know boost and/or intel :bug:, with a [:ticket:](https://svn.boost.org/trac/boost/ticket/9417).
Correct for obsolete c++11 feature

Older gcc implemented the monotic clock, which was subsequently removed from the (then tentitative)
standard for c++11.
Add some code to detect its usage and typedef it to steady_clock. The latter is in the accepted
standard.
:lipstick: from CMAKE_SOURCE to PROJECT_SOURCE