added LUA plot expression for line plots
preparation of LUA visualization phase for mesh plot handler
work in progress...
finished early prototype which supports mesh visualization phase in LUA.

Currently, it only decodes the input matrix into mesh input=patches.
added (untested!) handling of jumps to LUA mesh handler
first version of a LUA version of z buffer=sort for surface plots
updated todo
realized that the main file was missing during the last commits :-(