Add an option to show the sum of all used memory, including swap

[MurzNN]

Will be good to add an option to show the sum of all used memory, including swap, cuz some applications really use a lot of swap memory in time, but now it's not easy to catch them.

[pixelb]

We already show the total swap in the output from sudo ps_mem -S.
If you want an exact total of core + swap used you could use:
echo $(($(sudo ps_mem --total) + $(sudo ps_mem -S --total)))

[MurzNN]

I want to see the sum of "ram + swap" per program (and sort by this sum), not the total usage of swap.