ENH: Define CosmoTools cmake macros

Defined two macros: (1) to copy the headers in to the
global includes directory in the build tree, and, (2)
a macro to build a library. The resulting library will
either be a static library, a shared library or an object
library according to global user-supplied build parameters.
BUGFIX: Fix typo, remove redundant comma
ENH: Use copy_headers & cosmotools_library macros

Update CMakeLists.txt for common module to use the new macros
copy_header and cosmotools_library and simplify the CMake code.
ENH: Update code that builds single library

Update the CMake code to build a single monolithic library.