merged repcode search into BT match search

merged repcode search into BT match search

this version has same speed as branch `opt`
which is itself 5-10% slower than branch `dev`
(no identified reason)

It does not compress exactly the same as `opt` or `dev`,
maybe because it doesn't stop search after repcodes,
leading to sometimes better compression, sometimes worse
(by a small margin).

warning : _extDict path does not work for the time being
This means that benchmark module works,
but file module will fail with large files (and high compression level).
Objective is to fuse _extDict path into current one,
in order to have a single parser to maintain.