Merge stops into one

[answerquest]

Sample stops data:

stop_id	stop_name	stop_lat	stop_lon
GANGA1	Gangaram Bus stop	17.49489	78.33031
GANGA2	Gangaram Bus stop	17.49509	78.33022
GANGA3	Gangaram Bus stop	17.49502	78.33007
GANGA4	Gangaram Bus stop	17.49489	78.33036

User should be able to:

• multi-select these stops on map or on table,
• see them together (ie, other stops removed)
• pick one stop into which all selected are to be merged.

At system end, what this translates to:
Example: if GANGA3 was picked as the stop that everything has to be merged into.

• In stop_times table, rename all instances of GANGA1, GANGA2, GANGA4 into GANGA3.
• Delete stop_id's GANGA1, GANGA2, GANGA4.