Reimplement thread pool

* Thread pool has been redesigned and rewritten
* Beter API has been provided (now supports C++11 functionals)
* Unit, stress and performance tests has been written.
Adjust core's code to new thread pool API

Verification: build all configurations, run tests, play with demo.
Implement Windows-specific Timer class

This commit adds new Timer class written specifically under Windows
platform. Additionally, Timer is prepared for Linux implementation to ease
further development.

Timer tests are also added. These present basic usage and test some
specific cases.
[CRFIX]

This commit does following fixes coming from Code Review:
  * Boilerplates commented in one style
  * Added ImmediateStartStopTest
  * Fixed implementation of BasicUseTest according to discussed formula
  * Counter frequency is now acquired only once, during binary load
  * Division and casting is avoided in Timer::Stop()
  * Removed mStop from Timer class members
[CRFIX] Update #include directives
CRFIX

* TaskPtr -> TaskID
* style fixes
Merge pull request #41 from nfprojects/timer

Upgrade Timer class in nfCommon
Merge branch 'devel' of github.com:nfprojects/nfengine into threadpool

Conflicts:
	nfEngine/nfCommon/nfCommon.vcxproj
	nfEngine/nfCommon/nfCommon.vcxproj.filters
	nfEngine/nfCommonTest/nfCommonTest.vcxproj
	nfEngine/nfCommonTest/nfCommonTest.vcxproj.filters
Rename .h files to .hpp

Changes name to all .h files to .hpp. Additionally all #include directives
are changed to point to .hpp headers.
Merge pull request #55 from nfprojects/convert_h_to_hpp

Rename .h files to .hpp
Merge branch 'devel' into threadpool

Conflicts:
	nfEngine/nfCommon/ThreadPool.cpp
	nfEngine/nfCommon/ThreadPool.hpp
	nfEngine/nfCommon/nfCommon.vcxproj
	nfEngine/nfCommon/nfCommon.vcxproj.filters
	nfEngine/nfCommonTest/ThreadPoolTest.cpp
	nfEngine/nfCommonTest/nfCommonTest.vcxproj
	nfEngine/nfCommonTest/nfCommonTest.vcxproj.filters
	nfEngine/nfCore/Engine.hpp
	nfEngine/nfCore/PhysicsWorld.hpp
	nfEngine/nfCore/ResourcesManager.hpp
	nfEngine/nfCore/SceneManager.hpp
[CRFIX]
Merge pull request #39 from nfprojects/threadpool

Refactor Threadpool class
Merge branch 'devel' into packer1

Conflicts:
	nfEngine/Tools/Packer/packer.hpp
	nfEngine/Tools/PackerTool/packerTool.vcxproj
	nfEngine/nfCommon/nfCommon.vcxproj
	nfEngine/nfCommon/nfCommon.vcxproj.filters
	nfEngine/nfCommonTest/nfCommonTest.vcxproj
	nfEngine/nfCommonTest/nfCommonTest.vcxproj.filters