Merge branch 'hotfix-56'
IntervalVector() is now private
Fix bug #57
Merge branch 'hotfix-57' into develop
Merge branch 'hotfix-57.2' into develop
Merge branch 'hotfix-57.2' into ampl
Simplification of the use of AmplInterface
System(const AmplInterface& ampl)
Merge branch 'develop' of https://github.com/ibex-team/ibex-lib into develop
Merge branch 'develop' into ampl
remove some unused "resize" of IntervalVector
Merge branch 'develop' into heap2

Conflicts:
	src/arithmetic/ibex_IntervalVector.h
	src/strategy/ibex_Optimizer.cpp
size of CellBuffer is now "unsigned int)
DoubleHeap stable