Make ipython accept paths, not a single path
Make libzpython bindings accept multiple paths when using overrides
Prefer powerline bindings directory over fish_function_path
Write zero after writing current working directory in powerline.c
Do not omit running tests without ONLY_SHELL set
Remove tests/shell iff there are no failures
Run shell tests in an isolated environment
Add ext.*.components configuration support

Also fixes various problems in shell bindings.

Closes #969
Fix vim emulation module