add file modification list

docs/file-modification

@@ -0,0 +1,18 @@
+Buffers
+  modify
+    - if dirty alert user (immediately if focused, or on next focus)
+    - if clean update contents
+
+  remove
+    - mark file as unsaved (but maintains previous path)
+    - only unsubscribe from KQueue
+    - attempt to resubscribe after timeout (because of git weirdness)
+
+  move file
+    - update path
+
+  move ancestor directory
+    - update path on focus and save
+
+  recreated after remove (at same path)
+    - resubscribe on focus or save