1. Added an delimited number of retries upon exception for HTTP-related calls. 2. Make sure cowspeak does not throw an exception on Windows.

* [COWSPEAK,EXT] Added a newline before the cow's speech buble (so it always starts on a newline).
* [COWSPEAK,FIX] Use the new text_to_speech/1 predicate from OS_EXT in order to produce speech on different OS platforms (or to at least avoid exceptions being thrown on Windows).
* [HTML,NEW] Added http_open_wrapper/[2,3] and stream_to_html/[2,3] that introduce a counter that keep track of the number of reattempts. The idea is that process_exception/2 is allowed to retry for a certain URI or stream a delimited number of times.
* [HTML,EXT] Added retries (using call/1) for most exceptions. The number of attempts is counted inside the calling predicate.
* [OS_EXT,NEW] Added text_to_speech/1 which is intended to create a TTS process on various OS'es. Currently Unix work, assuming espeak is installed and Windows succeeds without doing anything.