csputils: correct constness of csp name constants
command: output more information in colorspace properties and simplify

Instead of trying to be clever to avoid outputting redundant
information, simply output everything that we have.
player: refresh OSD on track switching

Apparently, at least sub_reload was missing a refresh at all.
mf: don't limit filename length with PATH_MAX

Use an arbitrary constant instead, which is as good as PATH_MAX.

This helps us to avoid having to think about pull request #523.

Also fix a case where a potentially signed char was passed to isspace().
io: make MP_PATH_MAX private to win32 code

The win32 code is the only thing which actually needs this (and it's
used to make emulation of UTF-8 filename APIs easier).
audio: fix signedness of AF_FORMAT_S32P

This was marked as unsigned, but it's signed. Found by xylosper.
umpv: use --force-window

This makes it show a window even when playing audio-only files.
umpv: improve description
umpv: silence mpv terminal output

Now it does basically the same as mkv.desktop. Explanation is included
in the description comment.
Merge remote-tracking branch 'upstream/master'