Add blas chooser * src/blas_switch.mk: new file * binary-dist-rules.mk: add blas_switch as a windows dep * index.html, dist-files.mk: add ref to blas_switch * tools/makeinst-script.sh.in: add start menu blas switch menu * installer-files/README.html: add not about blas_switch

^settings\.mk
^usr/
^log/
^pkg/
^built-packages/
^installed-packages/
^wip/
^tmp-.*/

^autom4te\.cache/
^configure
^config\.status
^config\.log
^Makefile
^cmake-toolchain-file\.stamp

^cross-tools/
^gnuplot/
^octave/
^tools/makeinst-script\.sh
^tools/set-mxe-env\.sh