Changes

Refactor post_process of signature merging

The [post_process] function for signature merging was taking two linked
arguments: a [~destructive] flag and a [replace] function to apply only if the
flag was set to [true]. This commit combines the two into a single optional
function [replace] and clarifies some documentation comments.
 (commit: f9025a6)

Update comment and Changelog
 (commit: 706823f)

Address review comments

- Invert destructive and non-destructive cases
- Move the error inside the computation of the replace function
 (commit: b7a020f)

Update comment
 (commit: a4a7be5)