Previously, the index of the SketchCode instance in the list kept by
Sketch was kept, which isn't really robust.
With this change, Sketch.indexOfCode is no longer needed and is removed.
For determining if the current file was a sketch file, it previously
(indirectly) used a hardcoded "ino" comparison. Now, it uses
`SKETCH_EXTENSIONS` so it also applies to .pde files and the hardcoded
"ino" (and the methods leading up to it) can be removed.
This lets it use FileUtils.splitFilename and reference Sketch.EXTENSIONS
and the new Sketch.DEFAULT_SKETCH_EXTENSION directly, allowing to remove
a few helper functions.
Sketch is now called SketchController, since it didn't really represent
a sketch, but just handled the GUI-related stuff for a given sketch
(note that it is not strictly a controller in the MVC-sense, but it does
have a similar function). SketchData more accurately represented the
actual sketch, so it is now called Sketch. Below, the new names are
used.
Editor now keeps both a current Sketch and SketchController object, and
the Sketch object is created by Editor and passed to SketchController,
instead passing a File and letting SketchController create the Sketch.
Wherever possible, code now uses the Sketch directly (or indirectly,
through the new `SketchController.getSketch()`) and the accessors in
SketchController that merely forwarded to Sketch have been removed.
There are few things that now live in SketchController but should be
moved to Sketch (`isModified()`, `isUntitled()`), so some of the code
still has a dependency on SketchController that should be removed later.
This commit mostly renames classes, methods and variables, it should not
change the behaviour in any way.
