btrfs-progs: fi usage, change option for tabular output to T

We're going to use -t for tera- units prefix, same as 'fi df' does.

Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: fi usage, add switches to set output units

Same set of options as 'fi df': binary and decimal bases, human readable
options etc.

Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: fi usage, update manpage

Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: dev usage, add switches to set output units

Same set of options as 'fi df': binary and decimal bases, human readable
options etc.

Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: dev usage, update manpage

Signed-off-by: David Sterba <dsterba@suse.cz>
btrfs-progs: unify unit mode parameters and variables

Use unsigned type and a common name everywhere.

Signed-off-by: David Sterba <dsterba@suse.cz>