Makes plugins' STREAMFILEs not throw an error on non-existing .txtp
(normally written inside .m3u) treating it like a command/url-ish name.
This lets the TXTP parser to try to opening the virtual file with
commands, as 0-size TXTP with a formatted name is valid, like
"file.adx#l 1.0.txtp" ("play file.adx with 1 loop"), to allow quick
per-file config.
* Adds configuration options for ReplayGain as well as adds them to the configuration dialog box.
* Adds the volume to the info box (I'm thinking maybe this should later say "computed volume" and be preceded by a list of the tags associated to the file).
* Sadly, Winamp requires the methods related to opening, closing, seeking and getting data to basically be duplicated for the extended read functionality to work...
* ReplayGain is intentionally ignored in the extended read functionality so that Winamp ReplayGain calculator can function properly.
* NOTE: I think maybe the extended read functionality should ignore looping forever?
Needed to change how version.h was included to let it pick up the one from CMake's build location.
NOTE: Does not build with MinGW-w64 currently, does not have a way to build the audacious or XMPlay plugins.
It was implemented for Audacious only to open companion NWA files, but
current version has no need for it. In case there is some obscure thing
that needs it, Audacious's vfs.cc should translate or return realnames
transparently, without having to modify other streamfiles.
MSVC seems to compile with the UNICODE Windows flag enabled, unlike GCC,
causing some problems when Winamp's unicode is enabled, so until they
are fixed it can be enabled conditionally to build with GCC
