Some peg grammars could not capture values based on their position in a
larger grammar. This is a design limitation inheritted from LPeg, but no
longer needed as the replace mode is superseded by the accumulator mode,
which is more general if slightly harder to use.
This should speed up start time and reduce malloc/free
usage to about 15% of what is what previously for startup.
The current cost is slightly larger binary as the representaion
of the image is currently less compact than source code.
