Source Line support

[wearpants]

Add feature or option flag for reporting the source line & filename where the log message originated.

[MatthewScholefield]

For reference, here's the code to do it (Python 3):

import inspect

# Stack:
# [0] - this function
# [1] - caller
# [2] - ...
stack = inspect.stack()

# Record:
# [0] - frame object
# [1] - filename
# [2] - line number
# [3] - function
# ...
record = stack[2]
mod = inspect.getmodule(record[0])
mod_name = mod.__name__ if mod else ''
name = mod_name + ':' + record[3] + ':' + str(record[2])