Please add subroutine organization option

My idea is for an optional sidebar that lists all the functions in your code, with an option to view only a single function (void setup, void loop, custom functions, interrupt routines) instead of the entire INO, for the purpose of organization. A simple modification to the interface with some code to make sure new functions are added in the proper order.

Start by locating the Arduino IDE 1.x editor and interface code, then trace how INO functions such as setup, loop, custom functions, and interrupt routines are identified. The work is complete when an optional sidebar lists functions in source order and can display a selected function instead of the entire INO file.

Written by the indexing model from the issue text.