master: added several versions of Boolean SDP least square

On branch master
Changes to be committed:

      modified:   leastSquare_BSDP.m
      new file:   leastSquare_BSDP_v2.m
      new file:   leastSquare_BSDP_v3.m
      modified:   test_LSBSDP.m
Merge branch 'master' of https://github.com/jeffspence/iterative_hard_thresholding