Merge pull request #33 from CVerhoosel/plateexample

Plateexample
implement subvertex for 2d simplex
add cutplate triangular mesh option
fix laplace warning
fix maptrans bugs
fix gmesh reader, change edge order
rectililear: add code for nonuniform grid spacing
Merge pull request #34 from wijnandhoitinga/nonuniformmesh

rectililear: add code for nonuniform grid spacing
change library.Hooke and Orthotropic

callable changed:
old: stress( disp, geom )
new: stress( disp.symgrad(geom) )
Merge pull request #35 from wijnandhoitinga/library

change library.Hooke and Orthotropic
fix typo in orthotropic
add axis argument to function.product()
Merge pull request #36 from wijnandhoitinga/library

add axis argument to function.product()
fix elemsign missing ndim bug
Merge branch 'master' of github.com:nutils/nutils
fix boundary groups 1d structured domain
mesh.gmesh edges bugfix
add diag preconditioner, remove precon_cache
fix gmesh reader + small related bugs
Elemmean fix