Fish config refactor

Move things into sub-files and sub-directories
Add ensure_path function to make sure stuff doesn't get spammed multiple
times into the PATH

fish/functions/hybrid_bindings.fish

@@ -0,0 +1,6 @@
+function hybrid_bindings --description "Vi-style bindings that inherit emacs-style bindings in all modes"
+    for mode in default insert visual
+        fish_default_key_bindings -M $mode
+    end
+    fish_vi_key_bindings --no-erase
+end