Added a new (a bit experimental) cave rendering mode and
options to specify render mode
First lighting rendermode implementation.
Fixed testtextures.
Fixed makefile.
Merge pull request #21 from donkers/master

Visual updates: orientation selection & font
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.