linux/pulseaudio: Scale volume in Showtime instead of relying on pulse audio

Fixes problem with flat volume mode (Fedora11+)

Fixes #2128
Make it possible to use up/down keys during video playback to adjust per-file volume
hls: Detect and filter out bad PTS timestamps

Fixes #2159
Update fr_FR.lang
Don't even send seek events to players that don't want to seek
Don't deliver frames from demuxer thread. It might crash

Fixes #2183
ui: Trap "back" and "cancel" (escape) in popup requests

Fixes #2129
First version of a Duktape integration

Duktape is a EcmaScript (JavaScript) engine that I hope will replace
Spidermonkey eventually.

So far much of the Showtime APIs are lacking when plugins run in this engine.

Refs #2113
upgrade duktape to v0.10.0-328-g41366e7
ecmascript: Make it possible to get an array of all registered ecmascript contexts
linux: Log more info about current system
linux: Extract distribution from lsb_release and store in gconf.os_info
httpclient: Escape inproperly encoded redirect URLs

Fixes #2187
ecmascript: Improve prop support

* Add support for subscriptions

* Add support for pagination
httpclient: Rework Location header escape handling

Fixes #2187
htsmsg: Fix broken refcounts
duktape: Add support for searchers
duktape: Add support for Array of query arg objects
ecmascript/apiv1: Fix problem when no HTTP args are given
ecmascript: Support tracking destroy and correct delete of subscriptions