util/DynamicFifoBuffer: make GetCapacity() and Clear() public
Makefile.am: link libfs.a before libsystem.a

libfs.a depends on libsystem.a.
input/TextInputStream: move ReadBufferedLine() to util/TextFile.hxx
fs/output, fs/TextFile: move to fs/io/
fs/io/Reader: new interface
fs/io/BufferedReader: new class to replace class TextFile

The new class is pluggable, to prepare for gzipped database files.

For now, the TextFile class remains, and will be refactored away
later.
Merge branch 'id-3919' of git://github.com/ekroth/mpd
decoder/Mp4v2: fix crash with undefined error

When no track is found the error is now properly set.
Previously the calling function tried to log an undefined
error, which resulted in a crash. MPD falls back to
ffmpeg for unsupported tracks, such as ALAC.

This should fix issue 4051.