Fixes#90
__Problem__: VimwikiRenameLink does not rename dir1/toto url in dir2/tata
because the dirs (dir2 and .) were well crossed but badly inspected.
__Solution__: `blob(.ext*)` -> `glob(**/*.ext)` + find the relative URL
* Fasten: VimwikiRenameLink goes faster with cache
More: To compute old_url regex, use a cache dict because it is the same
for files in the same directories
* Util DeleteHiddenBuffer -> do not delete Vader buffer
* Test: Prettify: Util: teardown delete defined function
* Remove unnecessary trailing spaces
Note: list_VimwikiReturn.vader has some necessary trailing spaces
This change ensures the syntax is properly changed when running multiple
tests by removing the previously created temporary wiki and then
creating a new one.
