Fixed Size Unit

[JohnRobson]

This app is great, I wonder if you can allow to set a fixed size unit (instead of "human-readable"). I prefer to see all mounts in Gigabytes, instead of a mix of M/G/T, etc... Thanks. e.g.:

`| /efi | 1.022G | 0.583G | 0.438G |

| /mnt/sda | 3,400G | 1,900G | 1,500G |

| /mnt/sdb | 502.9G | 144.7G | 358.2G |`