Adding splitting input string to process_execute

Splits executable name off of the input string, stores that as the thread name to comply with that convention and so that the kill text is what we want.

Stores a new char* pointer to a string in args, this time starting where the args start.  Right this now this doesn't get handed off anywhere, so it dies all alone in a corner.

There's probably an issue with how this stuff is allocated.  Some pointers, and additionally another array exec_name, are allocated inside process_execute, which terminates before the thread scheduler calls start_process in order to finish setting up the process.  The pointers are fine, we're just passing uints around.  The array I think will be fine because it's allocated using malloc, but I'm not entirely sure how that works...