Merge pull request #19 from neozhangthe1/master

Implemeted Initializer
init mmap graph
create a delegate engine
remove tab and reorganize engine folder
folder path
initial version of mgraph
Use unique_ptr to fix some memory leaks
more formatting work
Merge pull request #22 wei/master

also retabbed files
first merge graph io
graph api
retab
add sync function for explicit save
add influence maximization
fix format
clear counter
rm using std
more std removed
clear warning
Merge pull request #26 from pondering/inf-max

Implement Influence Maximization