Preparation for #1.4.0 (#30)

- Fixed CPU affinity on Windows for NUMA and CPUs with lot of cores
- Implemented per thread configurable Multihash mode (double, triple, quadruple, quintuple)
- Rebased from XMRig 2.4.4

src/Cpu_mac.cpp

@@ -30,7 +30,7 @@
 #include "Cpu.h"
 
 
-void Cpu::init()
+void CpuImpl::init()
 {
 #   ifdef XMRIG_NO_LIBCPUID
     m_totalThreads = sysconf(_SC_NPROCESSORS_CONF);
@@ -40,6 +40,6 @@ void Cpu::init()
 }
 
 
-void Cpu::setAffinity(int id, uint64_t mask)
+void CpuImpl::setAffinity(int id, uint64_t mask)
 {
 }