Cleaning of heap test and bug fix in heap concept check (ticket #100)

* The dijkstra heap test's digraph is inlined into the source file
* The random sequences are fixed
* The content of the header is moved to the source file
* Only the binary heap is checked

 project (LEMON)

 enable_testing ()

 add_subdirectory (lemon)

 add_subdirectory (demo)

 add_subdirectory (test)