Esa logo added in PyGMO image
Fixed installation instructions
url added and apt-get specificity highlighted
Some fixes after the big merge
Improved documentation of spea2 and nspso.
Improved performances of spea2 by smartly reusing the neighbours matrix.
Moreover spea2 now correctly manage archive_size different from the population size
Merge branch 'multi_objective' of ssh://git.code.sf.net/p/pagmo/code into multi_objective

Conflicts:
	src/algorithm/nspso.cpp
Fixed compilation error with racing.
Fixed doc. Still missing con2mo and con2uncon.
Merge branch 'multi_objective' into development
Merge branch 'development' of ssh://git.code.sf.net/p/pagmo/code into development
Sphinx documentation completed for decomposition problem, pade, nspso and spea2
fixing compilation error in MSVC related to fmin/fmax and default parameters for multiple constructors in race_algo
Merge branch 'development' of ssh://localhost:1222/p/pagmo/code into development
[constriants] Fixed compilation warnings.
Fixed the bug with static array allocation not compatible with all compilers
Fixed racing test case on g5
Initial version of the tutorials
Added missing plots to the sphinx documentation
Fixed MSVC compilation errors on hv.c file. Fixed bug in constraints violation computation and test in con2mo and co_evolution. Adding of a third mode for the death penalty meta-problem with user defined penalty factors called WEIGHTED. Update tutorial on self_adaptive.
Removed assertion in migration policies that was always true