Some last minute bug fixes:

help()
- make sure we send the correct path to more since, if we change dir first "more help.txt" wont give
us what we want

exec()
- Fix the initial path algorithm to correctly stop if it finds whitespace before a / since that means
the path is an argument

main()
- Don't call ctl_d_handler if input is stdin (maybe we just EOF'd) and exit() if fopen fails to open
the batchfile