iss-25: Add initial IntervalDTO, MultiDimInterDTO, and their associated converters

[LucioTrincheri]

Add the initial implementation of IntervalDTO and it's associated converter, with the intention of having a common API for client code.
Also fixed #31, which was reproduced with @joaquinffernandez when setting a new clean environment and compiling sb-graph for the first time. Full log:

cc -I. -I../sbg-partitioner/src/3rd-party/boost/include -c sbg/interval.cpp -o obj/debug/sbg/interval.o -std=c++17 -Wall -Werror -Wno-reorder -O2 -D BOOST_PHOENIX_STL_TUPLE_H_ -D BOOST_MPL_LIMIT_LIST_SIZE=30 -D BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS -ggdb  
In file included from ./sbg/interval.hpp:38,
                 from sbg/interval.cpp:20:
./util/defs.hpp:79:14: error: ‘vector’ in namespace ‘std’ does not name a template type
 typedef std::vector<NAT> VNAT;
              ^~~~~~
./util/defs.hpp:79:9: note: ‘std::vector’ is defined in header ‘<vector>’; did you forget to ‘#include <vector>’?
./util/defs.hpp:37:1:
+#include <vector>
 
./util/defs.hpp:79:9:
 typedef std::vector<NAT> VNAT;
         ^~~
./util/defs.hpp:81:16: error: ‘VNAT’ does not name a type; did you mean ‘NAT’?
   member_class(VNAT, value);
                ^~~~
./util/defs.hpp:59:3: note: in definition of macro ‘member_class’
   X Y##_;                  \
   ^
./util/defs.hpp:81:16: error: ‘VNAT’ does not name a type; did you mean ‘NAT’?
   member_class(VNAT, value);
                ^~~~
./util/defs.hpp:60:3: note: in definition of macro ‘member_class’
   X Y() const;             \
   ^
./util/defs.hpp:81:16: error: ‘VNAT’ has not been declared
   member_class(VNAT, value);
                ^~~~
./util/defs.hpp:61:16: note: in definition of macro ‘member_class’
   void set_##Y(X x);       \
                ^
./util/defs.hpp:81:16: error: ‘VNAT’ does not name a type; did you mean ‘NAT’?
   member_class(VNAT, value);
                ^~~~
./util/defs.hpp:62:3: note: in definition of macro ‘member_class’
   X &Y##_ref();
   ^
./util/defs.hpp:86:10: error: ‘VNAT’ has not been declared
   MD_NAT(VNAT::iterator b, VNAT::iterator e);
          ^~~~
./util/defs.hpp:86:24: error: expected ‘)’ before ‘b’
   MD_NAT(VNAT::iterator b, VNAT::iterator e);
         ~              ^~
                        )
./util/defs.hpp:88:11: error: ‘VNAT’ does not name a type; did you mean ‘NAT’?
   typedef VNAT::iterator iterator;
           ^~~~
           NAT
./util/defs.hpp:89:11: error: ‘VNAT’ does not name a type; did you mean ‘NAT’?
   typedef VNAT::const_iterator const_iterator;
           ^~~~
           NAT
./util/defs.hpp:90:3: error: ‘iterator’ does not name a type; did you mean ‘strerror’?
   iterator begin();
   ^~~~~~~~
   strerror
./util/defs.hpp:91:3: error: ‘iterator’ does not name a type; did you mean ‘strerror’?
   iterator end();
   ^~~~~~~~
   strerror
./util/defs.hpp:92:3: error: ‘const_iterator’ does not name a type; did you mean ‘constexpr’?
   const_iterator begin() const;
   ^~~~~~~~~~~~~~
   constexpr
./util/defs.hpp:93:3: error: ‘const_iterator’ does not name a type; did you mean ‘constexpr’?
   const_iterator end() const;
   ^~~~~~~~~~~~~~
   constexpr
./util/defs.hpp:94:16: error: ‘iterator’ has not been declared
   void emplace(iterator it, NAT x);
                ^~~~~~~~
make: *** [Makefile:41: obj/debug/sbg/interval.o] Error 1

[joaquinffernandez]

I'll move DTO and API related sources to a separate Makefile as part of #38

[LucioTrincheri]

Done in fe8d3bb.

[joaquinffernandez]

Nice!! 👏 👏 Thanks for fixing #31
We will probably don't need the converter interface and a manager given that we are just going to use 3 converters, and it can be easily adapted if needed later on.

[LucioTrincheri]

#34 and #38 are resolved in this PR.