cache: merged cachetask and footagecache into one precache task

Since the actual auto-cache now happens elsewhere, this cleans up a lot of
dead code.

app/widget/projectexplorer/projectexplorer.cpp

@@ -31,7 +31,7 @@
 #include "core.h"
 #include "dialog/footageproperties/footageproperties.h"
 #include "dialog/sequence/sequence.h"
-#include "task/cache/footagecache.h"
+#include "task/precache/precachetask.h"
 #include "task/taskmanager.h"
 #include "widget/menu/menu.h"
 #include "widget/menu/menushared.h"
@@ -427,7 +427,7 @@ void ProjectExplorer::ContextMenuStartProxy(QAction *a)
 
   // Start a background task for proxying
   foreach (VideoStreamPtr video_stream, video_streams) {
-    FootageCacheTask* proxy_task = new FootageCacheTask(video_stream, sequence);
+    PreCacheTask* proxy_task = new PreCacheTask(video_stream, sequence);
     TaskManager::instance()->AddTask(proxy_task);
   }
 }

app/widget/timelinewidget/view/timelineviewbase.cpp

@@ -136,7 +136,7 @@ void TimelineViewBase::drawForeground(QPainter *painter, const QRectF &rect)
 
     // Get playhead highlight color
     QColor highlight = palette().text().color();
-    highlight.setAlpha(128);
+    highlight.setAlpha(32);
     painter->setPen(Qt::NoPen);
     painter->setBrush(highlight);
     painter->drawRect(playhead_rect);

app/widget/viewer/viewer.h

@@ -34,7 +34,6 @@
 #include "panel/scope/scope.h"
 #include "render/backend/opengl/openglbackend.h"
 #include "render/backend/renderticketwatcher.h"
-#include "task/cache/cache.h"
 #include "viewerdisplay.h"
 #include "viewerplaybacktimer.h"
 #include "viewerqueue.h"