/prog/ challenge: ``proper quotes''

Write a program that takes a text file and converts adirectional quotes into `` and '', i.e.

INPUT:
I turned my head around, with that casual smile all over my face.
"The stuff you said in your intro, how much of it was serious?"
With her arms crossed in front of her chest, lips sealed tight,
Suzumiya Haruhi kept her stern posture, staring right into my eyes.
"What 'stuff in my intro?'"
"The stuff about the aliens and all that."
"Are you an alien?"

OUTPUT:
I turned my head around, with that casual smile all over my face.
``The stuff you said in your intro, how much of it was serious?''
With her arms crossed in front of her chest, lips sealed tight,
Suzumiya Haruhi kept her stern posture, staring right into my eyes.
``What 'stuff in my intro?'''
``The stuff about the aliens and all that.''
``Are you an alien?''

Use whatever language you want. Bonus points for creativity and efficiency.

I'll start:
#include <stdio.h>

char *q[]= {"''", "``"};
main() {
 int c, i=0;
 while((c=getchar())!=EOF) {
  if(c=='"')
   printf("%s",q[i^=1]);
  else
   putchar(c);
 }
}

>> regexes are state machines too, you dumb cunt. Everything that can be run on intel's processor is a state machine. Thread is not over, we're submitting more state machines, and you should just click Return and enjoy other threads, along with your job you fucking asshat.

This is false. Intel processors can run turing complete code. If you don't understand this, stop shooting your fucking mouth off.