Classification-SD

[pulkitag22]

Added supporting files for self-dual* classification. This commit consist of functions

• to evaluate the exact SD representative for a given truth table;
• find out total number of functions in a particular variable numbered function. Similar to npn_enumeration.cpp (in ./examples/);
• other supporting functions to calculate the SD equivalent;
• test functions (in ./test/)

*Switching functions that become identical by self-dualization, non self-dualization, negation of variables or the function, or permutation of variables are called SD-equivalent.