Move all classes to their new locations

... assets too.
Update code to match moved classes

Edited both package names and import statements so that they now point
to the correct, new locations of the classes. Some import statements
were removed since classes now shared the same package, other import
statements had to be added since the classes were no longer in the same
package.

Had to change the following properties from `internal` to `protected`
after the classes that used them had to change package:

 * Input::_lookup
 * Input::_map
 * Input::_total

Had to change the following properties from `internal` to `public`
after the classes that used them had to change package:

 * FlxBasic._ACTIVECOUNT
 * FlxBasic._VISIBLECOUNT
Update paths for assets

Sadly, the paths are relative, but at least they are reliable.
Rename `FlxAnim` to `FlxAnimation`

Also updated any references to the class.
Merge pull request #205 from IQAndreas/organize-flixel

Organize Flixel into packages

Fixes #194

* Change main package from `org.flixel` to just `flixel`
* Organize Flixel's classes into several, more logically organized packages
* Rename `FlxAnim` to `FlxAnimation`