This is relatively hacky, but it's Christmas, so it's ok. This does two
things: 1. allow selecting two subtitle tracks, and 2. include a hack
that renders the second subtitle always as toptitle. See manpage
additions how to use this.
Until now, there were two functions to add input sources (stuff like
stdin input, slave mode, lirc, joystick). Unify them to a single
function (mp_input_add_fd()), and make sure the associated callbacks
always have a context parameter.
Change the lirc and joystick code such that they take store their state
in a context struct (probably worthless), and use the new mp_msg
replacements (the point of this refactoring).
Additionally, get rid of the ugly USE_FD0_CMD_SELECT etc. ifdeffery in
the terminal handling code.
Basically, reimplement --msglevel. Instead of making the new msg code
use the legacy code, make the legacy code use the reimplemented
functionality.
The handling of the deprecated --identify switch changes. It temporarily
stops working; this will be fixed in later commits.
The actual sub-options syntax (like --msglevel-vo=...) goes away, but I
bet nobody knew about this or used this anyway.
Since m_option.h and options.h are extremely often included, a lot of
files have to be changed.
Moving path.c/h to options/ is a bit questionable, but since this is
mainly about access to config files (which are also handled in
options/), it's probably ok.