Add support for the Weblate localization platform

[dpy013]

Introduction

Currently, NVDA uses Crowdin as its translation management platform. However, Crowdin has a number of accessibility issues. To address this, NVAccess even created the crowdin-accessibility project to centralize and report Crowdin's accessibility flaws.
To create a more comfortable working environment for translators and to allow translators who originally used Weblate to also access Poedit, it is suggested that Poedit add support for the Weblate localization system.

[dpy013]

Below are some posts from a mailing list discussion about Crowdin, including a compilation of Poedit issues.
Crowdin bug with target tag
Status of translation system, and new process for translating user documentation

[vslavik]

I will happily accept your PR adding such support, but I simply don't have the capacity to do it myself.