Use imglib2-cache-beta-12 and fix compile errors.

In particular, BlockingFetchQueues now needs to know the number of
consumers (fetcher-threads). To realize cache invalidate, it must be
possible to pause the fetcher-threads, which means driving the queue into
a state where all consumers are held in take(). To do that,
BlockingFetchQueues.pause() blocks until all (of the pre-defined number
of) consumer threads have arrived in take().

pom.xml

@@ -138,6 +138,8 @@
 
 		<!-- NB: Deploy releases to the SciJava Maven repository. -->
 		<releaseProfiles>deploy-to-scijava</releaseProfiles>
+
+		<imglib2-cache.version>1.0.0-beta-12</imglib2-cache.version>
 	</properties>
 
 	<repositories>

src/main/java/bdv/img/cache/VolatileGlobalCellCache.java

@@ -125,7 +125,7 @@ public class VolatileGlobalCellCache implements CacheControl
 	 */
 	public VolatileGlobalCellCache( final int maxNumLevels, final int numFetcherThreads )
 	{
-		queue = new BlockingFetchQueues<>( maxNumLevels );
+		queue = new BlockingFetchQueues<>( maxNumLevels, numFetcherThreads );
 		new FetcherThreads( queue, numFetcherThreads );
 		backingCache = new SoftRefLoaderCache<>();
 	}

src/main/java/bdv/img/hdf5/Hdf5ImageLoader.java

@@ -212,8 +212,9 @@ public class Hdf5ImageLoader implements ViewerImgLoader, MultiResolutionImgLoade
 				shortLoader = new Hdf5VolatileShortArrayLoader( hdf5Access );
 
 
-				final BlockingFetchQueues< Callable< ? > > queue = new BlockingFetchQueues<>( maxNumLevels );
-				fetchers = new FetcherThreads( queue, 1 );
+				final int numFetcherThreads = 1;
+				final BlockingFetchQueues< Callable< ? > > queue = new BlockingFetchQueues<>( maxNumLevels, numFetcherThreads );
+				fetchers = new FetcherThreads( queue, numFetcherThreads );
 				cache = new VolatileGlobalCellCache( queue );
 			}
 		}