Refactor vector system to be cleaner

- Move Vector, etc. into `.math` package
- Drop many methods that will be auto-promoted anyways, eg. with
`divide(int)` and `divide(double)` the first is now gone.
- Take Block vectors into their own class hierarchy
- Make it clear throughout the API what takes blockvectors
- many more improvements

worldedit-core/src/main/java/com/sk89q/worldedit/command/tool/BrushTool.java

@@ -189,7 +189,7 @@ public class BrushTool implements TraceTool {
             }
 
             try {
-                brush.build(editSession, target.toVector(), material, size);
+                brush.build(editSession, target.toVector().toBlockPoint(), material, size);
             } catch (MaxChangedBlocksException e) {
                 player.printError("Max blocks change limit reached.");
             } finally {