Fixed more bugs in tiling engine.

- Added GetTiles method in WaveFormControl; now filling holes with tiles
@ 100%. If all tiles @ 100% are present, zooming no longer displays
holes. However, we need a rect coverage alogrithmn to select tiles at a
better zoom level. However, the current code for the tiling engine is
now very solid and very fast, so it's just a matter of adding this
algorithmn to finally complete the job.
- Major code cleanup