Autoload : function on startup.

The newly added `:` command is implemented as a function (to avoid
increasing complexity by making it a builtin), but it is saved to a path
that does not match its filename (since its name is somewhat of a
special character that might cause problems during installation).
Directly probing the `colon` function for autoload causes `:` to be
correctly loaded, so doing just that after function paths are loaded
upon startup.

This is a hack since the CPP code shouldn't really be aware of
individual functions, perhaps there is a better way of doing this.

src/fish.cpp

@@ -384,6 +384,9 @@ int main(int argc, char **argv) {
 
     const io_chain_t empty_ios;
     if (read_init(paths)) {
+        // Additional initialization that must occur after paths are loaded
+        misc_init_with_paths();
+
         // Stomp the exit status of any initialization commands (issue #635).
         proc_set_last_status(STATUS_CMD_OK);