Address books are client specific.

This avoids redundant "if (x == NULL)" style checks and puts the onus on
the caller to use valid parameters.

99 % of these are just whitespace changes. Some unnecessary includes
removed as well

sflphone-common -> daemon
sflphone-client-gnome -> gnome
sflphone-client-kde -> kde
sflphone-plugins -> plugins

VideoV4l2List doesn't store the current settings anymore
Preferences are actually saved and restored
Properties (channel, size, rate) are all stored as strings
remove VideoV4l2Rate (it was only a float)

VideoV4l2List will have a thread monitoring devices insertion/removal with udev and will notify the preferences code in the daemon, and the client

Fix bug in VideoV4l2Channel::GetSizes() : mix class member and local variable (idx)

Print error messages in client dbus functions
Return NULL strings in client dbus functions in case of error, instead of uninitialized strings

numerator and denominator were inversed as far as ffmpeg's concerned

Implement preview widget using cairo
Exchange shared memory keys through DBus