* Expose files' begin and end pieces via RPC
This adds two arguments, `beginPiece` and `endPiece`, for each of the entries
in the `files` array of the RPC's `torrent-`get` method.
The point is to allow RPC clients to display a file's completion progress as
piece-based in addition to byte-based.
* Unify the line endings to the Unix style (LF only).
* Fix (where possible) or remove broken links.
* Improve the documentation.
Fix or remove broken links (depending on whether I could find a
working version of the resource).
Change all links to use HTTPS instead of HTTP.
Unify the capitalizations (e.g. uppercase abbreviations, capitalize
proper names and downcase other words).
Fix or improve some parts of the text, clarifying what is meant.
Improve some parts of the program examples (e.g. only use root
privileges where really required).