gsvd: new function imported from Octave-Forge linear-algebra package. * libinterp/corefcn/gsvd.cc: New function to the interpreter. Imported from the linear-algebra package. * CmplxGSVD.cc, CmplxGSVD.h, dbleGSVD.cc, dbleGSVD.h: new classes imported from the linear-algebra package to compute gsvd of Matrix and ComplexMatrix. * liboctave/operators/mx-defs.h, liboctave/operators/mx-ext.h: use new classes. * libinterp/corefcn/module.mk, liboctave/numeric/module.mk: Add to the * scripts/help/__unimplemented__.m: Remove "gsvd" from list. * doc/interpreter/linalg.txi: Add to manual. build system. * NEWS: Add function to list of new functions for 4.2.