Log Message:
Update gmpc to 0.18.0.
Based on PR#41471 by Guillaume Lasmayous.

Pkgsrc changes:
 * LICENSE=gnu-gpl-v2
 * Use system libsexy.
 * add option for support mac.
 * add buildlink3.mk for plugins.

Added features
* Global copy/paste system
  You can now copy songs from any song list and paste them in the play queue or
  the playlist-editor. The copy-paste system can also be used to move block of
  songs inside a playlist or between playlists.
* Easy Command
  Easy command is a gnome-do like interface to gmpc. This allows you to quickly
  add songs, play a certain songs or replace the play queue. More information .
* Windows Installer
  There is now a nice easy to use installer for gmpc on windows. It installs
  gmpc and all the needed gtk files, add menu option and uninstall program.
* Metadata Browser back/forward buttons
  The metadata browser now has browser-like back/forward buttons, allowing
  faster and easier navigation.
* Initial albumartist support
  If mpd provides it, gmpc now can use the albumartist tag to fetch metadata
  more reliably.
* Artist Image tooltip
  For the users that use gmpc in collapsed mode, there is a nice tooltip showing
  the artist image when hovering over the artist name in the player.
* Customizable quick links in metadata browser
  Via the gmpc wiki, hyper links can easily be added to the links section of the
  metadata browser. e.g. Wikipedia links are now included by default.
* Integrated search
  The search browser now gives you access to the magnatune and jamendo database
  as well (if plugins are installed). The search options also adjust to tags
  that actually can be searched.
* Initial Sticker Support
  MPD from git allows you to attach "stickers" to songs. GMPC can use \ 
this to
  rate songs.
  This is still very basic and will improve when stickers in mpd evolves.
* Server Information Page
  The serverstats plugin is now integrated into gmpc. This provides several
  statistics about your mpd database and configuration.
* Integrated favorites support
  The favorites plugin is now integrated in the playlist-editor. Press ctrl-
  enter to add the current playing song to the special "Favorites" \ 
playlist.

Bug fixes and Improvements
* Improved graphics, thanks to Chymera.
  * New Stylized covers.
  * No artist image.
  * Fetching artist image.
* Many translations updated and added. GMPC will be available in 28 languages.
* Reduced recourse usage.
  * Reduced the amount of unneeded image refreshing.
  * Play Queue grabs rows in blocks of X at the time. (Improves usage on high
    latency networks).
  * Main-loop based async downloader instead of manually iterating the loop.
* Better handling of file-encoding on windows.
* Less cpu intensive progress bar.
* Add songs to mpd in blocks of 16383 songs, so mpd does not run out of command- \ 
 buffer.
* Add clip when drawing images, avoiding small artifacts caused by scaling
  images.
* Compile time optional use of libsexy.
* Make search window integrate better.
* Don't save column width unless changed by user.
* Avoid race condition when listfield results are inconsistent.
* Fix drawing issues.
* Much more.

Internal changes
* Moved from libcurl to using libsoup for fetching data from the internet.
* Async downloader added.
* Internal vapi bindings so new features can be added coded in vala.
* All access to plugins via accessor functions.
* Removed Egg code that is now available in gtk.
* Moved everything, beside main gui, to GtkBuilder.
* Moved from custom popup code to GtkToolTip.
* and much more.

Plugins
* Jamendo
  * Use the new Downloader of gmpc, allowing for a quicker download and adds
    cancel option. This removes the libgio dependency.
  * Store the jamendo database in sqlite3. To gives faster and more complete
    access to all the songs. It also reduces the memory usage.
  * Integrate into gmpc Search browser
  * Make plugin work for windows.
  * Fix storing metadata on windows.
* Magnatune
  * Use the new Downloader of gmpc, allowing for a quicker download and adds
    cancel option.
  * Store the Magnatune database in sqlite3. To gives faster and more complete
    access to all the songs. It also reduces the memory usage.
  * Integrate into gmpc Search browser
  * Make plugin work for windows.
  * Fix storing metadata on windows.
* Last.fm
  * Allow user to set what metadata last.fm is used for.
  * Fix storing metadata on windows.
* MServer
  * Improve integrated feel in gmpc. (copy support for the copy/paste system,
    right mouse menu, etc.)
  * Send artist,album and title name to mpd. (via icy http header)
  * Drag and drop support. dn'd files from your file browser onto mserver
    browser to add files and folders.
  * If supported in gtk, allow the user to browse audio cd and add the tracks to
    the list. (Requires libgio to be working).