Lang - ensure sample loader finds mp3 files too

Author: samaaron

app/server/ruby/lib/sonicpi/sample_loader.rb

@@ -157,8 +157,8 @@ def ls_samples(path, recursive=false)
       @folder_contents_mutex.synchronize do
         res = @cached_folder_contents[path]
         return res if res
-        # match wav, aiff, aif, wave, flac, ogg and oga files
-        pattern = '*.{[wW][aA][vV],[wW][aA][vV][eE],[aA][iI][fF],[aA][iI][fF][fF],[fF][lL][aA][cC],[oO][gG][gGaA]}'
+        # match wav, aiff, aif, wave, flac, mp3, ogg and oga files
+        pattern = '*.{[wW][aA][vV],[wW][aA][vV][eE],[aA][iI][fF],[aA][iI][fF][fF],[fF][lL][aA][cC],[mM][pP]3},[oO][gG][gGaA]'
         if recursive
           res = Dir.chdir(path) { Dir.glob("**/#{pattern}").map { |p| File.expand_path(p) } }.sort
         else