Changes to prepare for handling of functions
Use index of hedge in fixpoint
Fix some function importing stuffs, add few graph tests
Continue fixing function importing, test it in test_data
Import functions only once
Call stack to detect recursion
Hgraph: Recursive function handling
Test_data: use recursive calls
Hgraph: fix what was failing
Merge branch 'function_import'

Conflicts:
	src/tlambda_to_hgraph.ml
Test_data: fix for the change of int representation