[rbp/omxplayer] Avoid resampling in audio_mixer

audio_mixer output defaults to 44.1kHz. Set it to output of audio_decode to avoid a resampling step
This restores the behaviour prior to #2801
Revert "[rbp] Always use the aspect ratio from file."

This reverts commit 7f5d3ede514f30552e42464c29227d570b38ed8a.
[rbp/omxplayer] Use aspect ratio from video decoder

We don't get a valid aspect ratio from tvheadend with mpeg2 files, but the decoder does know, so use that.
This also supports streams where aspect ratio changes (e.g. at commercials) (with firmware from 25 June or newer).
Replace deprecated CodedID and CODEC_ID by their av prefixed counterparts.
[fix] Ensure tvshowmatching regexes are run caseless
Merge pull request #2878 from aballier/codecid

Replace deprecated CodecID and CODEC_ID_* by AVCodecID and AV_CODEC_ID_* everywhere in xbmc code.
Cosmetic: Remove case distinctions in tvshowmatching regexes
[rbp/omxplayer] Check total memory, and if plenty use full size buffers

omxplayer has used a quarter sized video buffer and a half sized audio buffer for the file reading message queue, compared to dvdplayer.
This is required on 256M boards, but is unneccessary on 512M board. So we query the memory size and use full size buffers if possible.
[rbp/omxplayer] Make audio_render configurable as the clock master

By default audio_render is the clock master, and if output samples don't fit the timestamps, it will speed up/slow down the clock.
This tends to be better for maintaining audio sync and avoiding audio glitches, but can affect video/display sync.
The other option makes audio_render the clock slave, and it has to drop packet or output silence to maintain sync.

As both settings have some advantages, and as this mode more accurately defines whether playback is synced to display or audio, I've used the GUI setting "sync playback to display" to control this.

The previous use of "sync playback to display" didn't have any benefits, and was never recommended.
[rbp/omxplayer] It never makes sense to delay in audio/video players

We are not synchonous with frames submitted so sleeping won't help anything
[rbp/omxplayer] Remove fixPreroll parameter

The preroll only affects when the clock component starts. It doesn't affect the reported timestamps,
so adjusting timestamp by the preroll is incorrect
[rbp/omxplayer] Use timestamps given to gpu as GetCurrentPts

Currently the timestamps gpu is using and those returned from GetCurrentPts can diverge, making decisions inaccurate.
Make sure they use the same timestamps by bringing the timestamp code up from OMXVideo to OMXPlayerVideo.
[rbp/omxplayer] More care with marking GetCurrentPts as invalid
Merge pull request #2917 from popcornmix/avoid_resampling_mixer

[rbp/omxplayer] Avoid resampling in audio_mixer
Merge pull request #2922 from popcornmix/audio_clock_master

[rbp/omxplayer] Make audio_render configurable as the clock master
Merge pull request #2924 from popcornmix/remove_fixpreroll

[rbp/omxplayer] Remove fixPreroll parameter
Merge pull request #2923 from popcornmix/remove_delay

[rbp/omxplayer] It never makes sense to delay in audio/video players
Merge pull request #2892 from ronie/weather-fixes

update wunderground addon
Merge pull request #2919 from popcornmix/aspect_from_decoder

[rbp/omxplayer] Use aspect ratio from video decoder
Merge pull request #2918 from popcornmix/big_buffer

[rbp/omxplayer] Check total memory, and if plenty use full size buffers