fixed includes
Revert "fixed includes"

This reverts commit 3471d6408ced073ef470dce0d78d8cb31f3ff388.
introduce Zero_or_False utility and resolve circular dependencies issues in load, fix #733
fix some warnings in linalg
fix some unsigned/signed comparison warnings
redeclaration of variable i removed
rename argument to lapack functions in reference benchmarks from 'i' to 'info', fix #744
Issue #746 - operator[] on pack expression
Fix broadcast on pack
commented line removed and assert statement modified
Revert "commented line removed and assert statement modified"i comparing signed and unsigned ints
This reverts commit ce6e85d0d9962224561d65f951e29e87670ecbb1.
alankelly <alankelly@live.com>

commented line removed and assert statement modified
Added missing include in constant hierarchy
fix eval_linsolve warning fiasco + improve formatting of file
Quick-fix for failed gather_includes builds when cross compiling (missing exceptions support).
Applied the same quick-fix to move_reuse and postconfigure as for gather_includes.
(note to nt2 devs: there seems to be duplication between the CMakeLists.txt files for the three tools)
Fixed/updated remaining code affected by the timing code changes.
Added attempts to prevent the compiler and/or the CPU from reordering and/or removing calls to timing functions.
Changed the default time unit to microseconds.
Added and used the priority_booster_t utility class.
Added more todo and implementation notes.
Further improved stability/accuracy of the timing functions overhead (still not "perfect", especially for now()).
Optimized the median<>() function template and (temporarily) moved it into the now.cpp.
Switched to the rand48 PRNG (as it is faster) and (temporarily) moved the reusable PRNG functions into the now.cpp.
Minor other refactoring and stylistic changes.
Created a virtual interface class for benchmarks. Used it to make the perform_benchmark function a non template and (temporarily) moved it to now.cpp.
Used the perform_benchmark(_impl) function in now.cpp to accurately calculate the timing functions overhead (this now produces stable/reproducible results).
Minor CT optimization.