Format bytecode listing on client side

[mejedi]

Backend to produce a self-descriptive bytecode format, to be converted to text on client side.

This will enable:

• better constants display (currently: FNEW 0 0 ; <main.lua>:1);

• branch target discovery independent of the text format (FORI 1 => 0008);

• to visually discriminate between different classes of immediate integer arguments in instructions (MODVN 5 4 0 );

• to assign meaningful names to prototypes (based on the target of FNEW assignment + debug info).

Doing it on client side will make it possible for the old saved states (sharing) to benefit from new application features.

Pre-req for #7