Replaces all uses of `TEMPLATEPATH` and `STYLESHEETPATH` in core with `get_template_directory()` and `get_stylesheet_directory()`.

Add `@deprecated` annotations to `TEMPLATEPATH` and `STYLESHEETPATH` definitions.

Props obenland, aaroncampbell. 
Fixes #18298.

Built from https://develop.svn.wordpress.org/trunk@28563


git-svn-id: http://core.svn.wordpress.org/trunk@28389 1a063a9b-81f0-0310-95a4-ce76da25c4cd