Remove the forward_list::reverse() call.  It was not necessary,
because pls_parser() already reads the playlist in reverse order.

Replaces GLib's g_ascii_strcasecmp().

Overload the name.

Micro-optimization.

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

This plugin has been defunct ever since Last.fm changed their
protocol.  Since there is no volunteer willing to fix the plugin, I'm
removing it now.

Replaces struct playlist_provider.

Use only ConfigData.hxx in plugin sources to reduce header
dependencies.

Replaces GLib's GError.

Simplify the error path, because the other allocations may fail.