* Add new `update-authors.js` tool that traverses commit history using
  `git log` and creates authors list.

* Decouple common functions into a module shared between tools.

* Add `.mailmap` file with proper names and emails of active
  collaborators.  This file is automatically parsed by Git so that
  `git log --format='%aN <%aE>'` won't show duplicate entries in case
  something was committed with misconfigured Git.  E.g., without this
  file @tshemsedinov appears twice in the list, as Timur Shemsedinov
  and as tshemsedinov, but with mailmap applied Git automatically
  coalesces these entries to use the full name only.

* Don't use a Set together with an array, O(n^2) instead of O(n*log(n))
  is fine for such tool but the code is shorter.
* Use a regular for-of loop instead of reduce.

New commit message for 8915cd7:

tools: generate authors list automatically

* Add new `update-authors.js` tool that traverses commit history using
  `git log` and creates authors list.

* Decouple common functions into a module shared between tools.

* Add `.mailmap` file.  This file is automatically parsed by Git so that
  `git log --format='%aN <%aE>'` won't show duplicate entries in case
  something was committed with misconfigured Git.  E.g., without this
  file @tshemsedinov appears twice in the list, as Timur Shemsedinov
  and as tshemsedinov, but with mailmap applied Git automatically
  coalesces these entries to use the full name only.  This file now
  includes the active collaborators (@tshemsedinov for a reason and
  @aqrln and @belochub just in case) and proper names and emails for
  two contributors who committed with invalid ones.