GSL-2.6

GSL 2.6 release (stable version) with cmake script.

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Use GSL-2.6 as the codebase.

1. include copy %Codebase%/gsl folder into %Repo_Root%/include, remove make files.

2. source

   1. copy %Codebase%/<sub_module_dir> folder into %Repo_Root%/source

   blas block