fix sorting by size in shared files table

gui/src/main/groovy/com/muwire/gui/SizeRenderer.groovy

@@ -0,0 +1,29 @@
+package com.muwire.gui
+
+import javax.swing.JComponent
+import javax.swing.JLabel
+import javax.swing.JTable
+import javax.swing.table.DefaultTableCellRenderer
+
+import net.i2p.data.DataHelper
+
+class SizeRenderer extends DefaultTableCellRenderer {
+    SizeRenderer() {
+        setHorizontalAlignment(JLabel.CENTER)
+    }
+    @Override
+    JComponent getTableCellRendererComponent(JTable table, Object value,
+        boolean isSelected, boolean hasFocus, int row, int column) {
+        Long l = (Long) value
+        String formatted = DataHelper.formatSize2Decimal(l, false)+"B"
+        setText(formatted)
+        if (isSelected) {
+            setForeground(table.getSelectionForeground())
+            setBackground(table.getSelectionBackground())
+        } else {
+            setForeground(table.getForeground())
+            setBackground(table.getBackground())
+        }
+        this
+    }
+}