Improve initialization (#2)

* Improve initialization
* Force initialization during startup
* Rename to autovenv.fish

Author: zhou13

conf.d/autoenv.fish renamed to conf.d/autovenv.fish

@@ -38,7 +38,7 @@ function applyAutoenv
     set _tree (dirname $_tree)
   end
   # If we're *not* in an active venv and the venv source dir exists we activate it and return.
-  if test -z "$VIRTUAL_ENV" -a -e "$_source"
+  if test \( -z "$VIRTUAL_ENV" -o "$_autovenv_initialized" = "0" \) -a -e "$_source"
     source "$_source"
     if test "$autovenv_announce" = "yes"
       echo "Activated Virtual Environment ($__autovenv_new)"
@@ -66,13 +66,17 @@ function applyAutoenv
   end
 end
 
-# We need to run AutoVenv on the initialization of each session.
-if status is-interactive
+# Activates AutoVenv based on directory changes.
+function autovenv --on-variable PWD -d "Automatic activation of Python virtual environments"
   applyAutoenv
 end
 
-## AutoVenv Function.
-# Activates on directory changes.
-function autovenv --on-variable PWD -d "Automatic activation of Python virtual environments"
-  applyAutoenv
+set --global _autovenv_initialized 0
+
+# Activates AutoVenv on initialization of the session after sourcing config.fish.
+function __autovenv_on_prompt --on-event fish_prompt
+  if test "$_autovenv_initialized" = "0"
+    applyAutoenv
+    set --global _autovenv_initialized 1
+  end
 end