[openbox] client lists with submenus

[Alexey Korop]

Hi, All

    I adapts to the 3.5.0 and send to Bugzilla the "final" versions of 
the two my patches: bug 4795 that improve submenus with default item and 
bug 5239 that in the client-list[-combined]-menu replace the normal 
client items by the submenus with default item "Activate" and 
additionnal items "Send to desktop" and "Close".
    Now these patches are based on the current state of Danas's "Master" 
branch.

https://bugzilla.icculus.org/show_bug.cgi?id=4795
https://bugzilla.icculus.org/show_bug.cgi?id=5239

Yours truly Alexey