As discussed on the mailinglist [1] the tiling support is
removed from KWin. The main reasons for this step are:
* it is unmaintained
* it is a mode not used by any of the core KWin team
* original developer said at Akademy 2012 that he is not
  interested in picking up the work again
* tiling has quite some bugs, e.g. multi screen not supported
* is conflicting with other concepts in KWin, e.g. activities

There is ongoing work to get tiling supported through a KWin
script, which is a preferred way as it does not influence the
existing C++ code base.

[1] http://lists.kde.org/?l=kwin&m=133149673110558&w=2
BUG: 303090
FIXED-IN: 4.10
REVIEW: 105546