Rewroted for clear

Hi

I rewroted memstat.sh with:
 - do not use temporaries files
 - do not usage cat/awk/paste/bc/cut/rm/ls/sort/uniq/wc/id utilities
 - allow pid list
 - allow non-root usage
 - more fast and clear

If interested see ftp://ftp.simtreas.ru/pub/my/memstat.sh