[Review board] let the plasmoids specify the ratio they wants in keepRatioMode

[Loïc Marteau]

Hi !

Actually plasmoids can ask to keep their aspect ratio to a square when 
they are in panels.
The idea is to let them specify the aspect ratio they want, not only square.

Lock/logout plasmoid take too much width place and providing such 
capatabilities will make life easier for such applets.

keepRatioMode already exist for plasmoid and for the moment is only used 
on the desktop (when activated, if the user resize the plasmoid the 
mouseevent code in applethandle force the ratio to be kept in place).

We can use keepRatioMode when plasmoid is in panels too. For the moment 
in my patch plasmoid choose the desired ratio when he call 
setAspectRatioMode, perhaps it is better to have proper getter/setter 
for the desired ratioMode and keep setAspectRatioMode() at his current 
state ?

So Square and ConstrainedSquare became only specific cases of 
keepRatioMode and KeepAspectRatioConstrained with desired ratio equal to 
1. As a result, perhaps we can remove this two modes completely ?!

This is only a first *draft*.

here is the link to the patch on the review board :
http://reviewboard.vidsolbach.de/r/53/

Cheers !