remove erroneous executable bits

benchmarks/2d/world.geo

benchmarks/step/Block.stp

benchmarks/step/wrenchnut.stp

benchmarks/stl/PelvisHEMI.stl.gz

contrib/kbipack/compute_normal_form.c

contrib/kbipack/gmp_blas.c

contrib/kbipack/gmp_blas.h

contrib/kbipack/gmp_matrix.c

contrib/kbipack/gmp_matrix.h

contrib/kbipack/gmp_matrix_io.c

contrib/kbipack/gmp_matrix_io.h

contrib/kbipack/gmp_normal_form.c

contrib/kbipack/gmp_normal_form.h

contrib/kbipack/kbihnf.m

contrib/kbipack/kbisnf.m

contrib/kbipack/licence

contrib/kbipack/readme

tutorial/t10.geo

utils/solvers/perl/GMSH_CLIENT.pm

utils/solvers/perl/solver.opt