For #8 : Tileset editor window mostly working

* Tileset editor window appears with notes, buttons, tilesetproperties, etc.
* Introduces a skeleton and placeholder for TilesetDisplay.
* The text controls on the right aren't autosizing correctly, and they're too small

Midstream on #8 - sizing problems.

midstrean on #8 - sizers mostly fixed, still some min sizes to set

Resizing works as expected now and minimum sizes enforced, moved the buttons for #8

For #8 midstream, all resizing works as expected now
Midstream on #8 : Reverted to using ImageDisplay and cut out the properties change event handler, to show how it looks before getting horked up
Revert "Midstream on #8 : Reverted to using ImageDisplay and cut out the properties change event handler, to show how it looks before getting horked up"

This reverts commit f6f635a5839a15054f3c812ea4ea37566a0bf426.
Midstream on #8 : Grid drawing works as expected now, but the TilesetPropertiesChangedEvent is not bubbling up like it should, so the grid can't change
Midstream on #8 : TilesetEditor, TilesetProperties and GridDisplay all interact as expected at this point
Midstream on #8 : Added grid darkening when you click on a cell and the tile name edit box.
Midstream on #8 : Storing names of individual tiles works now, GridDisplay can be queried for the selected tile index, tile bitmap, size of rectangle list, and a complete set of chopped tiles
Midstream on #8 : Confirmation dialog when changing dimensions because it will force tile names to reset
Midway on #8 : Export button now exports all split tiles into a directory
Midstream on #8 : Got saving to JSON working, moved the tileset saving functionality to Tailor\Tileset
Midstream on #8 : Made Tailor::Tileset handle all the size/space/pad attributes, simplified the flow of those attribute changes, renamed things from *_image when they actually use Wx::Bitmap
Midstream on #8: Got the 'Load' button working (Save/Load, yay) and renamed the rest of the buttons
Reintegrated main window