Fixed the issues with the 15R1 block.

A few more construction steps added.

Updated Icons with pictures for the 13r to 12r transistion blocks.

Updated Icons for 6r and 5ri blocks.

Remove xml load error for non existent content

Updated to support the skins system.

All Curved blocks and panels should now support skins.

Windows and other similar blocks forced to be airtight.

Removed LOD at level 3 to help people with lower settings on their graphics cards.
Added new block sets: Curved Panels to complement Glass for 15r and 6r, Curved Glass and Panel Mix for 15r.
Added Icons for all that were missing them.

Reversed the direction of the tint on the windows, now tinted from the outside.
Added LOD at level 3.
Added extra detail to the window frames.

Added 6r Windows.
Changed texture on inside of windows to match the standard windows.