bug: fixed filters string to include '

Author: harshsankhla18

filter.c

@@ -7,7 +7,7 @@
 int main(int argc, char *argv[])
 {
  // Define allowable filters
- char *filters = "bgrsivtdGBo";
+ char *filters = "bgrsivtdGoB:";
 
 
  char filterArr[argc-3];