Updated more ledge stuffs.
Fixed alpha values being incorrect.
Fixed incorrect ledge collision detection/response. As a consequence, test area has been modified.
Fixed "suddenly, no response" bug. The cause of it is the "unprocessed" ticks are in the negative, which I never clamped it to being positive always.
Modified the test area again.
Updated the doc.
Added biome color to specific tiles.
Moved color codes to WorldConstants.
Fix another "suddenly, no response" bug. This time, unprocessed can go up to NaN.
Added water to doc.
Added water. This commit allows the game to support bitmap animation.