Notes for SWAP

1. Performs $x \leftrightarrow y$
2. An index file input line looks like:

   <ID> <incX> <incY> <source file> <author name>
   

3. For unit stride case, the complex routine calls the real equivalent with N*2.
4. The main use of this routine that I am aware of is row-swapping in factorizations, so this is one routine that it would make sense to optimize the arbitrary increment cases, if it were possible.