Documentation cleanups:
- capitalization of the titles
- moved Coding style docs to Sphinx
Disable Parboil/bfs for LLVM 3.4 for now.
Add Barrier::startsWithBarrier() helper function.

Cleanup the style of some C++ language files.
Improve the CFG pretty printer so it can highlight interesting
basic blocks and draw parallel region boxes nicely.

More C++ style fixes here and there.
Added info for future release managers. Collected it from
Wiki and past experiences.
Implement sqrt using the sqrtf(). This enables Clang to replace it
with llvm.sqrt* intrinstics in case looser math flags are used to
build the builtin library.

__builtin_sqrt() is not replaced as intrinsics this way for some reason.
TODO: fix this in Clang.
tce: Disable the support for NaNs when building the kernel library to
e.g. generate llvm.sqrt* intrinsics from sqrt() (instead of a math lib
call) which allows us to replace it with a call to sqrt HW operation selectively.
tce: do not use --vector-backend by default.
Clang does not recognize __builtin_sqrt* in CGBuiltin.cpp (around line 1285)
to be a call to sqrt and cannot selectively convert it to the llvm.sqrt.*
intrinsics with looser math flags. Therefore we have to call it as a libcall
so it regonized it. For the double we still call the __builtin_sqrt() to
disambiguate from the sqrt() to avoid infinite recursion. Probably the
correct fix is to patch CGBuiltin.cpp to recognize also the call via
__builtin_sqrt*.
Fixed piglit reference output
Clean now removes libOpenCL.la
Devices: fix wrongly placed assert and device count iteration
Updated the support ViennaCL version.
Update the piglit README
Partial fix to building for LLVM 3.5.
Still broken with LLVM 208752.
Merge branch 'master' of https://github.com/pocl/pocl
Devices: fix wrongly placed assert and device count iteration
clCreateImage: Remove unecessary freeing step when buffer allocation failed
create also half float version of select in kernel library
clCreateImage: fix returned value when format is not supported