blas and lapack on single file

(compiles faster)
Possibility to use external lapack/blas

One can either use external libraries with:
CPPGLAFS=-D__PLUMED_EXTERNAL_BLAS and -D__PLUMED_EXTERNAL_LAPACK
and
DYNAMIC_LIBS=-lwhatever_appropriate

or, with no flags, use internal libraries.

The two flags are independent (one can e.g. use external blas
with internal lapack)