Add PythonDocUtil project layout/files.

vim/scripts/PythonDocUtil/*
	-Add dir-structure for the `PythonDocUtil` plugin.

vim/scripts/PythonDocUtil/autoload/PythonDocUtil.vim
	-Add the plugin's backbone, with most of the necessary functions
	present.
	-Add significant content to `InsertFunctionComment()`.
Add return/yield/exception documentation.

autoload/PythonDocUtil.vim
	-Add `s:GetPythonBlock()`, to implement:
	`s:DocumentReturnOrYieldValue()` and `s:DocumentExceptions()` in
	`s:InsertFunctionComment()`.
	-Move all `s:IsOn*` functions into `GenerateDocstring()`.

indexer.py
	-Remove accidentally committed file.
Add documentation to PythonDocUtil functions.

vim/scripts/PythonDocUtil/autoload/PythonDocUtil.vim
	-Add documentation to all completed functions.