vmmap command: show offset for single addresses (#795)
vmmap command: show offset for single addresses (#795)

* vmmap command: show offset for single addresses

Changes vmmap display so when it is invoked with a single address, it
will also display its offset.

Before this commit:
```
pwndbg> vmmap $rsp
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
    0x7ffffffde000     0x7ffffffff000 rw-p    21000 0      [stack]
```

After this commit:
```
pwndbg> vmmap $rsp
LEGEND: STACK | HEAP | CODE | DATA | RWX | RODATA
    0x7ffffffde000     0x7ffffffff000 rw-p    21000 0      [stack] +0x1fb60
```

* Remove ugly hack :)
anthraxx/pwndbg,anthraxx/pwndbg,pwndbg/pwndbg,pwndbg/pwndbg,anthraxx/pwndbg,anthraxx/pwndbg,pwndbg/pwndbg,pwndbg/pwndbg