* CrypTFlow2 code

* Some small corrections.

* Updated License to 2020

* Updated repo README to include SCI (CrypTFlow2) and moved CrypTFlow2/ to SCI/

Co-authored-by: Nishant Kumar <nishant.kr10@gmail.com>

* With new compiler changes

* After backend interface cleanup

* Interface cleaned up

* Removed funcSSCons and FLOAT_PRECISION fix

* funcSSCons right fix1

* Cleanup of several things ; Athos and EzPC changes for 2PC

* Residual changes

* More changes

* One left file

Added license in files of sub-folders of EzPC; modified codegen of ezpc to output a autogenerated comment for each compiled file; synced up the test-suite/precompiled_output folder with actual compiled output changes.

Fix in ezpc.sh: add ezpc signed library file only when codegen is either unspecified or specified as ABY or CPP. Plus, diff of precompiled output used to differ because of an earlier change: updated all the precompiled output files.

Fix for input output in other functions giving error when compiled with ABY: made a global variable named role and assigned the same in main.

Updated ezpc.h for logical and arithmetic right shifts: arithmetic right shift now uses logical as subroutine; logical was earlier not padding the output shares correctly - fixed that.

BUG DESCRIPTION: Arithmetic right shift used to lead to segfaults when used with ABY.
FIX: - Updated function arithmetic_right_shift in file ABY_example/common/ezpc.h
     - Adding correct gate ids before feeding the new share value to create a share.

More specifically, some of these changes include:
- Added extern function support to ezpc.
- Added SecureNN as backend to ezpc.
- More bug fixes.
- All test_suite examples' precompiled-output are updated with new compiler changes.
- Added an updated and more complex sample compiled test file in ABY_example.

Tests done
- "make runtest" works fine for all test_suite examples.
- Sample code in ABY_example is also tested to be working with latest ABY.