DFT IDFT Calculator

_Changelog_ 
--> initial build 
--> support 4 & 8 pt dft idft 
--> support DIF, DIT both 
 
_note:_ 
input format: a+bj 
for real number "a" : a+0j or -a+0j 
for complex number : a+bj or -a+bj 
for complex negative number : a+-bj or -a+-bj 
--> support complex + real values 
--> all butterfly output results