back to square one

- Now, fixed thought on flo-fem, no meddling of remeshing concepts. So
each xelement doesnt have any parent or children, instead they have
subelement arrays (subelement types and connectivities to main element)

- in this way, global arrays' sizes remain unchanged for all quantities
(nodes, edges, faces, main elements); output would go through main
elements and plot according to main element cnc and its sub element cncs

- updated almost all modules (xedge to xbrick, and added xwedge_lamina
and xbrick_lamina modules), and added subelement module, all unfinished
and untested

- a good way to do laminate element is not yet fully seen

- future steps should start from basics, i.e., finish basic element
routines first, before building laminate element