Bring back clang in Travis CI

- Add working Boost 1.53 PPA
- Use default CFLAGS
spelling mistake. Classname Clipper3D is case-sensitive in MSVC2010.
Don't use optimized build flags for Travis
Kinfu 30% performance drop bugfix. In the modified CUDA files references to functions Block::reduce with an argument plus() were removed and a new reduce function was added instead.
Removed dead code in esf.hpp with potential memory access violations
Merge pull request #168 from szagoruyko/kinfufix

Kinfu 30% performance drop bugfix
Merge pull request #170 from jakobkirkegaard/master

Removed dead code in esf.hpp for fixing issue #87
Namespace, prefix, and lowercase sse functions

This fixes a compile error on OS X where the
MIN function collided with a MIN macro.

The fix namespaces the functions in pcl::common,
prefixes the functions with `sse_`, and lowercases
them to prevent interefence from macros.
Revert "Merge pull request #92 from nfioraio/master"

This reverts commit 789fb082b59b15b471b6de397862b85f04400e56, reversing
changes made to b16dff11b484ffd4491cd383d0c2c63798ebf3fd.
Moved sse.hpp from common/pcl/common/impl/sse.hpp to common/include/pcl/sse.h.