Add feature to go back to the previous function after using goto_definition

[bien6mui]

Hi @lintingbin2009,

It will be good if you could add a button to go back to the previous function after using goto_definition.

In default of Sublime we had a feature to do it ({ "keys": ["alt+keypad_minus"], "command": "jump_back" }), but it is not so good because when we click somewhere in our source code then it will come back to that position (not go back to the previous function).

Thanks for your plugin, it is really good for me when coding with Erlang.
/Bien