client API: improve comments
lua: add a minor helper function
encode: add a missing \n to a log call
encode: write 2-pass stats only per-packet

The stats were retrieved and written on every encode call, instead of
every encode call that actually returned a packet. ffmpeg.c also does it
this way, so it must be "more correct". Fixes 2-pass encoding.
client API: remove outdated comments
lua: add helper function for printing a table

Although this is something really basic, Lua's standard library doesn't
provide anything like this. Probably because there are too many ways to
do it right or wrong.

This code tries to be really careful when dealing with mixed
arrays/maps, e.g. when a table has integer keys starting from 1, making
it look like an array, but then also has other keys.
manpage: document how the client API retrieves the complicated properties

"Complicated" as in they use sub-properties, and using MPV_FORMAT_NODE
allows an application to retrieve all information at once.
client API: include the reason in MPV_EVENT_END_FILE

Otherwise, the client API user could not know why playback was stopped.

Regarding the fact that 0 is used both for normal EOF and EOF on error:
this is because mplayer traditionally did not distinguish these, and in
general it's hard to tell the real reason. (There are various weird
corner cases which make it hard.)
command: remove extended information from --list-properties

This used to display the property type, but it was not always correct or
even available. The way the property mechanism works, we can know this
only at runtime.
options: sort --list-options

Until now, --list-options printed options in random order. There
literally wasn't any logic in its order, they just appeared as they were
declared. So just sort them.

Note that we can't sort them in advance, because for certain things
internal to m_config, the order actually matters.

Also we're using strcasecmp(), which is bad (locale dependent), but this
is output intended for human consumption, so it's not a problem.
manpage: fix --vf=scale options
terminal: pretty print modules for --msgmodule
options: don't sort sub-option help output

Commit 2c2c1203 sorted the output of --list-options, but the same code
ias also used for listing sub-options, such as --vo=scale:help. For sub-
options, the order actually matters.
mp_tags: move generic mp_tags stuff into its own .c/.h files in common/

rename add_metadata to the more genera/descriptive mp_tags_copy_items_from_av_dictionary
m_property: add missing convenience macros for int64 and double subproperties
mpv_node_map: add some convenience functions

also make sufficiently generic mpv_node functions in m_options globally accessible.
m_option: make print_node actually do something
talloc README: more human readible api reference
vf: add two new functions for sending vfctrls down the filter chain

vf_command_all: send command to all filters
vf_command_by_name: send command to named filter
vf_control_by_label: send command to a filter with given label
vf_lavfi: fix ffmpeg deprecation warning for avfilter_graph_parse

use avfilter_graph_parse_ptr for ffmpeg