make skip commercials an option in the webif (default to on)

Conflicts:
	src/webui/static/app/dvr.js
dvr: added initial support for libavformat muxing

Conflicts:
	src/webui/extjs.c
	src/webui/static/app/dvr.js
Merge remote-tracking branch 'tvheadend/tvheadend/master' into testmerge2

Conflicts:
	debian/control
	docs/html/config_dvb.html
	docs/html/overview.html
	src/access.h
	src/dvb/dvb_adapter.c
	src/dvb/dvb_service.c
	src/htsmsg_json.c
	src/htsp_server.c
	src/main.c
	src/muxer/muxer_pass.c
	src/psi.c
	src/webui/extjs.c
	src/webui/static/app/acleditor.js
	src/webui/static/app/capmteditor.js
	src/webui/static/app/chconf.js
	src/webui/static/app/config.js
	src/webui/static/app/cteditor.js
	src/webui/static/app/cwceditor.js
	src/webui/static/app/dvb.js
	src/webui/static/app/dvr.js
	src/webui/static/app/epg.js
	src/webui/static/app/epggrab.js
	src/webui/static/app/ext.css
	src/webui/static/app/iptv.js
	src/webui/static/app/status.js
	src/webui/static/app/tableeditor.js
	src/webui/static/app/tvadapters.js
	src/webui/static/app/tvheadend.js
	src/webui/static/app/v4l.js
	src/webui/static/multiselect/ddview.js
	src/webui/static/multiselect/multiselect.js
	src/webui/static/multiselect/resources/multiselect.css
	src/webui/webui.c
Revert: Save channels upon add
Revert some unfinished changes related to access.c
Adding sky UK mappings for NDS
Merge remote-tracking branch 'origin/pr/206'

Conflicts:
	src/webui/extjs_dvb.c
	src/webui/static/app/dvb.js
[PR-206] dvb: extend the multi-frontend PR to include cleaner support.

Generally this is intended to be used such that a user can select which
frontend they wish to enable. However in theory with clever configuration,
configure one adapter then the other and enabling close fds and disabling
idle scan, it might be possible to use both frontends.

But since TVH doesn't do any form of arbitration strange errors might
occur if you try to access both frontends at the same time (which for
most such adapters is not possible).

Conflicts:
	src/dvb/dvb_adapter.c