[Writer] Set default precision for output to std::numeric_limits<double>::digits10.
[MeshIO] Removed setting the output precision explicitly.
Changed the output precision of floating point values in gli files.
use CMAKE_CXX_COMPILER_VERSION to get clang version
change the minimum CMake version to 2.8.8 to support CMAKE_CXX_COMPILER_VERSION
use cmake version 2.8.8 for travis CI.
Merge pull request #184 from norihiro-w/fix-cmake-clang-version

Get clang version in CMake
Merge pull request #183 from TomFischer/OutputPrecisionChange

Output precision change