Improve the merge algorithm

[le-git-imate]

Description of issue or feature request
le-git-imate re-implements the git merge algorithm in JS. We need to revisit the merge component to address all potential issues. A list of things that we should look into is as follows:

• Check if all necessary merge algorithms are implemented, or we did not ignored them by mistake.
• Check if all buffer assignments work correctly such as is_eol_crlf, xdl_classify_record, XdlClassifier, xdl_prepare_ctx, xdl_build_script, xdl_recmatch.
• Check if predefined values are chosen correctly such as XDL_LINE_MAX, XDL_MERGE, XDL_GUESS_NLINES.

Current behavior

• There might be several merge cases that the current implantation is not able to address.

Expected behavior

• Make the merge algorithm more reliable and fix potential issues listed above. You can start by looking into there refs: [1, 2, 3].