fix: use namespace nta/utils, using std

to avoid weird std::swap() -- unknown namespace?? :P
c++11: migrate nta/utils

nullptr, override
c++11: migrate nta/tests headers
c++11 migrate nta/regions headers
c++11 migrate nta/os headers
fix nta::UInt32 causing problems in namespace nta

undefined nta, so #include nta/types/types.hpp where defined
fix: include for is_subsequence_of
fix: include for size_t
fix: unknown macro ITERATE_ON_ALL_ROWS
fix: include for Log2
fix: include stddef.h for size_t
C++11 migrate nta/engine headers

some overrides, pass-by-value
remove old Cells2 class

this was unused
remove unused code OLD_ALGORITHM

this #ifdef'ed code was unused
Merge branch 'cleanup' into c++11-clang-modernizer
fix: include for istream ostream
include Log.h for NTA_CHECK macros
fix for size_t
fix: include for free()
fix include math.h for exp()