Profile functionality proposal

[wintermute]

Hello!

My daily routine often requires me to connect my laptop to different 
sets of monitors or projectors (often multiple). The problem is, in it's 
current state, xfce-display-settings is unable to set their settings 
according to my desires automatically, so I have to configure them 
manually every time, which may be painful. So, I came up with a 
solution.

I designed an addition to current display-settings dialogue, which 
allows a user to save current configuration to xfconf as a named 
profile. The combobox allows to choose any saved profile, which can be 
applied or deleted. This way, a person may have different configurations 
saved for his equipment, which can be easily applied without manual 
reconfiguration.

Also, I added an "Auto" button to minimal dialogue. This button will try 
to guess the profile based on the equipment connected and apply it. I 
forked a github repository, and you can review my work here: 
https://github.com/ololorin/xfce4-settings/tree/master/dialogs/display-settings

Please, tell me, what you think about it. :)