Fixing newer C++ Version

[datvo06]

I have made the following changes:
(1) Simplifying the template arguments (e.g., ALLOC is removed for classes in which the default std::alloc can be used)
(2) For conv_hash_type in element_parser, this was coupled with other hashmaps (e.g., level_one_hmap), once we update /release the original edges, the key also got removed. I updated this by copying the key in case of std::string.
(3) Update the code to use total_max_pattern while mining for random_max_graph instead of "120,400" in graph_test
(4) I also added CMake and some C++ 17 features. Project can now be build with

cd test && mkdir build && cd build
cmake ..
make

Thanks for reviewing my changes.
Dat