Update to L3DT 2.3c

Bump-mapped lighting is now available in L3DT Professional. Here is a screenshot to whet your appetite:

Each land type may have their own unique bump-maps, which are specified in the land type definitions within the climate files. So far I have only upgraded the 'temperate' and 'arctic' climates to include bump-mapping, with the rest to follow at a later date. Here, by the way, is an image of the arctic climate with 8× light-mapping and textures:

While some benefits may be observed for regular low-resolution light- and texture-maps, the best results from bump-mapping are achieved at 8× resolution or higher.