Log Message:
Update openbox to 3.5.2.

While here:
* add hard dependency on Python.
* add options for image support, enable recommended imlib2 by default.
* fixes missing bump of API_DEPENDS to 3.5.
* easy and better handling for config files.

3.5.2:
  * Fix crash in theme rendering code, and in theme parsing code.
  * Maximize windows without borders to fill the whole screen, don't leave
    a one-pixel empty space. (Bug #5996)

3.5.1:
  * New translations: Afrikaans, Belarusian, Interlingua, Hebrew, Romanian,
    Greek.
  * Updated translations: Italian, Serbian, Spanish, Czech, Hungarian, Turkish,
    German, Arabic, Polish, Dutch, Lithuanian, Portuguese, Estonian.
  * SVG icon support. This is optional, depending on librsvg being installed.
  * Allow application rules to control window size with a new <size> tag.
  * Allow application rules to pick a monitor for new windows without forcing
    a position.
  * Allow non-interactive focus cycling with a new <interactive> tag.
  * New LeastOverlap window placement policy replaces the old default
    behaviour. It finds a place on a given monitor that overlaps as few
    windows as possible. Contributed by Ian Zimmerman.
  * Improved Xinerama behaviour.
  * Correctly interface with latest gnome-session for Gnome/Openbox X sessions.
  * Allow third-party control of window opacity in compositing managers.
  * Improved themeing options. Contributed by Dave Foster.
  * Add <monitor>, <title type="regex">, <title \ 
type="exact"> and
    <activedesktop> options to If action.
  * Addresses bugs #4661, #5506, #5186, #5758, #5410, #5228, #5277, #5731,
    #5746, #5737, #5419, #5721, #5711, #5385, #5500, #4992, #5443, #5518,
    #5444, #4782, #5237, #5228, #5173, #5203, #5246, #5180, #5179, #5150,
    #5132, #4937, #4889, #5253, #3769, #5819, #5811, #5081, #5426 among others.