* updated the AM and BM 
* Added a new mapping function 
* Added a join function
* Added a helper function to print tuple elements
* Added new tests to test functions, namely
** create AM
** mapping
** join 
** filter
Resolved the conflict in tests.ml

Merge branch 'master' of https://github.com/niksu/MoanaML into niksu-master

Conflicts:
	tests.ml
Merge branch 'niksu-master'
Removed accindental <<<HEAD keyword
* Added new test for the use of composite join of two join functions.
* corrected test 6
* Fixed mapping function in AM; was missing filtering of tuples
* Refactored the join function for more complex cases,
 namely for it to work with multiple variables
 
* added function to print variable mappings in AM

* Added function to print BM

* took sel_arg function outside join function scope
* Added test 9 to test more complex join function

* refactored the code to include print_bm and print_mappings functions
* Removed some commented code and extra white spaces