Added skeleton & build scripts for BF compiler.

The compiler code including lua headers can now be built successfully.
Removed opcode SUB and PREV.

First, opcode SUB and PREV are removed due to the fact that they can
be replaced by ADD and NEXT with negetive parameter.

In this commit, I disabled build of bfi and bfc. Also, test codes are
updated to reflect the changes.
Modify interpreter codes according to opcode change.

The interpreter (bfi) code is modified to conform opcode change.

Also, discovered and fixed an error that compiler internal state is
not corrected reset. Such internal state error may cause error in
compiled code, resulting bad results.