osmo_interact: improve vty transcript language by a regular rexex

Currently the transcript language understand 3 different tokens:
... (ignore all lines until the following line matches)
... !REGEX (ignore all lines except REXEX)

But to support osmo-stp with different compile options, the
vty help is indented with different amount of spaces depending on the compile options.
To support those add a regular regex using the prefix !r!

E.g.
```
OsmoSTP(config-cs7-as)# ?
-  description       Save human-readable description of the object
vs
+  description               Save human-readable description of the object
```

To use the new regex, the line would be:
```
!r!  description[ ]+Save human-readable description of the object
```

Further all regex special characters needs to be escaped.
```
  description   Save human-readable description of the object (for humans)

!r!  description[ ]+Save human-readable description of the object \(for humans\)
```

Change-Id: Iadcd7a8c3677548a6405e098fe53d0614ef2012c
---
M osmopy/osmo_interact/common.py
1 file changed, 15 insertions(+), 2 deletions(-)