Avoid GLib.

Replaces g_uri_parse_scheme().

To replace g_strdup().

Replaces GLib's g_str_has_prefix().

This implementation behaves mostly identical to old parser.
Few observable differences:
- There are no option groups (single group is used for all options)
- Option --stdout is hidden (it has been obsolete for a long time)
- MPD executable name (mpd) is hardcoded for simplicity

Not supported by libc++.

Required for building with libc++.

Replaces GLib's g_ascii_strncasecmp().

Replaces GLib's g_ascii_strcasecmp().

Overload the name.

Replacing GLib macros.

Micro-optimization.

Micro-optimization.

Replaces GLib's GError.

ReusableBuffer is more generic.