update issue #36
start spreading local dof contribution from element, boundary and periodic
into their own files
not yet functional
Merge branch 'develop' into feature/mortar
update issue #36: fixed compilation, now the fun (mortar) starts
update issue #36: added Mortar/NoMortar (default : NoMortar) interface to
FunctionSpace and propagate to DofTable. Update DofTable definition with the
new template argument
update issue #36 start work on functionspace interface in composite case
update issue #36 , retrieve mortar example using product space, will use that
as a testcase
Merge branch 'develop' into feature/mortar

Conflicts:
	feel/feeldiscr/functionspace.hpp
fix isSiblingOf(), much check that both this and m have sub mesh data
introduce SSpace to compute Pk-1
fix compilation
 - introduce mortars<> 
 - implement mortar in 2D 
 - work in composite case
++log
more fix for isSiblingof()
update issue #36 
added mortar space definition `Moch<N>()`
still lots of work to do and in particular allowing to go through the dof
table without hardcoding the type of finite element. In hp or mortar methods
the polynomial order changes in the elements
update issue #36
updated mortar test
added begin() and end() free function to iterate over mesh entities using
range for loop c++11 construct
fix internalElements()
add subclass for sub-space (Pk-1) construction