clean up fixes for building Intel FFTW wrappers for imkl v11.1.x or more recent
fix combining PRECISION and interface flags
fix allopts, should be list of lists rather than a list of strings
add debug info, fix type for elements of allopts, code cleanup
fix composing list of build options, explicitely specify compiler=intel if Intel compilers are used
create temporary directory for building FFTW wrappers in build dir
Merge pull request #1 from boegel/imkl_11.1.x_fftw_mpi_wrappers

cleanup for imkl v11.1.x FFTW wrapper support