Merge pull request #26 from StephaneSeyvoz/nmf-style

Idl-frontend-cpp to allow including C++ headers from interfaces.
Cherry-picked commits from the "frontend" branch of "master" + version fix.
Merge pull request #27 from StephaneSeyvoz/nmf-style

Fix: mind-plugin.xml ID: not backend but frontend ! (copy-paste is bad)
Add ZigBee sensor example for nmf c++ model.
Add ZigBee sensor example in pure c++.
Rename to ZigBee sensor minimal model.
Remove the runtime path.
Add doc book for nmf example.
Fix compilation error.
Add obj folder.
Merge pull request #28 from StephaneSeyvoz/nmf-style

Fix virtual method prototypes to restore virtual = 0
Temporary remove the dependcy with the ext lib.
Merge branch 'nmf-style' of https://github.com/Mind4SE/mind-cpp into nmf-style
Some corrections.
Add external library for linux and win32.
Add hpp and cpp user code example in documentation.
Re-organize the cpp examples.
Move the cpp example documentation from the example's pom to the mindcpp's pom.
Use "prepare-package" maven phase in order to generate cpp example documentation.
Create the folder "GeneratedCode" in the ZigBeeSensor cpp example.
Add Makefile in order to build cpp examples.
Base mindc++ mindcommon.hpp on mind mindcommon.h
Do not include GeneratedCode folder in the packaged example.