Added NodeTree infrastructure to decouple job creation from targets and remove Target class hierarchy.
New algorith for parallel compilation.

First build a tree of nodes then search for a compilable node only when there are
some free slot for a job.
Remove dead code in meique.cpp.
Removed use of Target class from meique.h/cpp.
Remove Target family classes.

Known regression: precompilehooks isn't working anymore.
Remove pthread dependence from LuaState and LuaLocker.
Removed all hash related stuff from meique, let go to the timestamp approach.
Trigger recompilation of depending targets when needed.

Fixes issue #22.
Remove unused nodes from node tree.
Use C++11 thread routines instead of pthread.

Also fix a dead lock caused by the refactor.
Better job names, still ugly but better than before.
Use _output from lua instead of get the output name direct from Compiler interface.
Remove luaPushTarget from NodeTree and use the one on MeiqueScript.
Only run custom targets when needed.
Fix library targets output name.
Link libraries and trigger custon targets only when needed.
Check dependencies of a file to decide if it should be compiled.

Bug: Doesn't check the include paths yet.
cacheTargetCompilerOptions should be private.
Print nice progress status again :-).
Move NodeTree instance to JobFactory implementation.