[Dev-luatex] C cleanup / lua errors / other news

[Taco Hoekwater]

The new stuff in this afternoons' commit:

* C code is cleaned up a bit

* Lua errors are now processed using TeX's "normal" methods

* Lua Syntax errors and Runtime errors no longer destroy the
   associated interpreter

* Other Lua errors (memory alloc failures) quit the entire
   TeX run, with fatal error message.

* tex.print() now writes to the tex pool directly, the
   intermediate buffer is removed. The main advantage is that
   there is no longer an arbitrary limit on the length of
   the return string.

* The lua interface to the tex arrays now accepts 16-bit
   indices.

That is it for now. Work on luatex will continue monday.

Cheers, Taco