service: Restore error clearing on Agent reply

If the invalid key error is not cleared on Agent reply, the
service cannot be reconnected.
wispr: Fix refcounting issue
wifi: Always Scan hidden APs

We should scan hidden AP even if the AP is not marked
as autoconnectable so that the user is able to connect
to it manually.
wifi: Ignore duplicate hidden APs

We must not add duplicate entries to list of hidden AP.
There can be more that one service file for each AP if
we have multiple wifi cards in the system.

Fixes BMC#24779
service: Send updated properties after ServicesChanged

Updated service properties are not sent before the new service
has been announced in a 'ServicesChanged' signal.

Fixes BMC#21285
service: Always zero the timeout id when timer triggers

The timer id was not cleared in case the signal creation failed.
git: Do not ignore connman manual pages
doc: Manual page for connman
doc: Manual page for connman configuration file
Release 1.6
device: Refactor device scan function

In wifi plugin this means that we combine three wifi scan
functions (normal, fast, hidden) into one scan function.
vpn: Accept also "true" or "1" as a boolean value

Currently user is able to set the boolean VPN config value
only by setting the variable to "yes". This is not very
intuitive so accept also the value of "true" or "1".
provider: Return VPN gateway IP address

If 'provider->host_ip[0]' is set, it contains the
resolved IP address. If not set, the 'Host' property
already contains an IP address.
l2tp: Get VPN gateway resolved IP address

We should not use the Host variable from provider as it can
contain a non-resolved address.
pptp: Get VPN gateway resolved IP address

We should not use the Host variable from provider as it can
contain a non-resolved address.

Fixes BMC#25658
pptp: Fix PPTP option typo

Fixes BMC#25660
gdbus: Fix compilation error if macro "error" is defined

The variable "signature" used in error is not defined and "args" is now
a struct instead of a string.
inet: Properly remove IPv4 address and set interface down

The interface was not properly set down and thus the services
were not removed.

Fixes BMC#25659
service: Do not report error twice

In request_input_cb(), __connman_service_indicate_error() unconditionally
reports an error via agent after determing the service state. The error
reporting and user connectable state will be properly handled by
service_indicate_state().
session: Update overview doc

Update to the new D-Bus API and the simplified connection
algorithms (state).