Slightly modify the interface of Circulation and Preflow (#266)
in order to synchronize them to the interface of NetworkSimplex.

Circulation:
- The "delta" notation is replaced by "supply".
- lowerCapMap(), upperCapMap() are renamed to lowerMap() and upperMap().
- Value is renamed to Flow.

Preflow:
- Value is renamed to Flow.

#cmakedefine HAVE_LONG_LONG 1

#cmakedefine HAVE_LP 1

#cmakedefine HAVE_MIP 1

#cmakedefine HAVE_GLPK 1