Issue #1458 - fix unint variable.
Issue #1403 - ensure adapter config is properly loaded.
Add new capabilities field to determine what optional features are included.
webui: add some processing of capabilities for dynamic tab inclusion.
Issue #1446 - fix --disable-cwc checks.
Issue #1446 - fix --disable-linuxdvb.
Fix #1427 - webui: Added reverse proxy support.

This includes a next webroot command line argument (using -W) and
some minor mods to the core HTTP/WebUI code to support this. Most
of the mods are pretty trivial and hopefully nothing will break
too badly.
added supported codecs to htsp server capabilities
Merge remote-tracking branch 'upstream/master' into transcode_v2

Conflicts:
	src/htsp_server.c
	src/main.c
	src/webui/static/app/tvheadend.js
changed the subscription parameter name maxHeight to maxResolution
ignore reconfiguration reguests for mkv muxer.

Multisegment matroska files do exist but I am not sure if they are
supported by many media players. If we treat it as an error, the recording
will be split into several files. If we ignore it, the recording will only
be one file, but we might miss new tracks, or 16:9 --> 4:3 changes.
allow using libav for muxing, but no transcoding
added new htsp method called getCodecs that returns a list of encoders available to the transcoder
[transcoding] set correct frametype
Issue #1459 - fix removal of all autorec recordings on startup

There were 2 issues here:
- recent changes meant that recordings were purged on every startup
- long standing issue meant complete recordings were removed on
  removal of an autorec rule (which I don't think was intended).
[transcoding] set default codec context
set default gop size (keyint) to ~1x fps
[transcoding] improved default bit rates and buffer sizes a bit
Merge remote-tracking branch 'upstream/master' into transcode_v2
fix bug where the first vorbis frame would have a negative duration. fixes playback in chrome