Emergency Calls (4th round)

Here is a new proposal for emergency calls handling.

Steps in handling emergency calls:
- subscribe to modem online notifications (add modem online watcher)
- an emergency call detected (phone number is emergency number)
- increment emergency mode
- advertise "EmergencyMode" property change on D-Bus (first call)
- set modem online if it's in offline mode (minimal setup)
- adevertise "Online" property change on D-Bus
- if modem is not online postpone making the call, otherwise make the emergency call
- when modem online notification comes and there is postponed call request make the emergency call
- when an emergency call ends decrement emergency mode
- set modem offline if it was set online due to the emergency call (last call)
- advertise "Online" property change on D-Bus
- advertise "EmergencyMode" property change on D-Bus (last call)

Note: emergency calls with SIM card (network registered or unregistered) and without SIM card are supported.

Andras Domokos (4):
modem: add modem online-offline watch
modem: add EmergencyMode property
modem: move dial_request_cb function
voicecall: add emergency call handling

 src/modem.c     |  180 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/ofono.h     |   12 ++++
 src/voicecall.c |  175 +++++++++++++++++++++++++++++++++++++++++++----------
 3 files changed, 334 insertions(+), 33 deletions(-)