handle seek during pause and stop

drop needless debug printf

implement seeking This adds the internal management of the seeking, as well as the decoder backends bits.

bits, rate and channels are unsigned match the struct sio_par

declare local functions as static

keep track of current position and total duration

improving error reporting makes the player process optionally send back a string describing the failure to provide a better and more coincise error message. This turns the syslog message(s): amused: unknown file type amused: failed to play, skipping /home/op/pics/phos.jpg into: amused: unknown file type; skipping /home/op/pics/phos.jpg

don't sio_start if we're not stopped

don't POLLIN, we only care about POLLOUT

don't change params if they're the same avoids a sio_stop in the common case of switching from song that needs similar params (such as tracks in the same album.)

inline player_init

switch to a non-blocking usage of sndio

free the imsg in player after handling, plugs a memory leak

inline player_enqueue

s/audio_init/player_init was the only function to disrespect the player_* namespace (well, excepting play). while here also don't mark those two as static, they were the only static functions in the file. I'm not trying to enforcing private symbols here.