[Telepathy] tp-qt4 ContactCapabilities and RequestableChannelClasses API proposal

[Andre Moreira Magalhaes]

Simon McVittie wrote:
> +/**
> + * Start a request to ensure that a video call with the given
> + * contact \a contactIdentifier exists, creating it if necessary.
> + *
> + * See ensureChannel() for more details.
> + *
> + * This will only work on relatively modern connection managers.
> + *
> + * \param contactIdentifier The identifier of the contact to call.
> + * \param withAudio true if both audio and video are required, false for a
> + *                  video-only call
> + * \param userActionTime The time at which user action occurred, or QDateTime()
> + *                       if this channel request is for some reason not
> + *                       involving user action.
> + * \param preferredHandler Either the well-known bus name (starting with
> + *                         org.freedesktop.Telepathy.Client.) of the preferred
> + *                         handler for this channel, or an empty string to
> + *                         indicate that any handler would be acceptable.
> + * \sa ensureChannel(), createChannel()
> + */
> +PendingChannelRequest *Account::ensureAudioCall(
>   
ensureVideoCall :P, copy/paste error

Regarding Capabilities, I mainly liked how you proposed it, I would just 
do some cosmetic changes here and there, starting by changing 
CapabilitiesBase to just Capabilities. I would use Base/Abstract for 
classes that need to be reimplemented by someone, which is not the case.

The rest is ok for me +1

BR
Andrunko