1.7.1

Changes

• A better filter effect without performance issue instead of translucency is finally implemented for the sheet switcher.
• Add repeating and permanent mode on the default sheet. Now the default sheet also have full functions except changing name (which will be never used I think). Notice: Some work has been done to assure the compatibility with all the old versions but will be removed in the future.
• Fix an old bug of memory leak when the page content reload.