Added a new (a bit experimental) cave rendering mode and
options to specify render mode
First lighting rendermode implementation.
Fixed testtextures.
Fixed makefile.
Small template enhancements, moved some CSS from Javascript to CSS-File.
Moved images to the template/icons directory.
Fixed small night lighting bug.
Improved multithreading performance by better work assignment.
Fixed some small texture mistakes.
Updated orientation icons

Icons are now 24 x 24 pixels, RGB colour with some AA