fixed a bug when compiling void functions

layout of modules. To use this new compiler, you need a matching stdlib,
i.e., revision 1042 or newer.

wrapping/unwrapping/typechecks and defines the SACarg type.

without option -noprelude

code can not lead to further optimization potential.
Furthermore, I added STAT_WHY which prints why a function is
reoptimized.

which is needed when compiling prelude itself (whas automagically
before) and handy when debugging small programs.

we now introduce explicit copy functions whenever type_constraint is applied to convert between scalar/non-scalar representations

uses static inlined C functions to perform the nodetype
checks for each assignment and gives and error messages
and segfaults whenever a mismatch is detected.

and their corresponding return type does not match. This is done to
ensure that the backend emits corresponding representation adjustments.