omit stack traces from particular files prototype

[ivanov]

@NorthIsUp

there are two places to make changes - one for the stack trace as it is
printed by ipython on error, the other as it is printed by ipdb.

you can verify that it works like this: (note the missing tmp.py entries)

In [1]: !cat tmp.py                                                                                                                                                                                                                                                                                                                                                                                                  
import bar

def foo_test():
    bar_test()

def bar_test():
    bar.foo_bar()



In [2]: !cat bar.py

def foo_bar():
    1/0

In [3]: import tmp

In [4]: tmp.foo_test()
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)
<ipython-input-4-f50710bfc43f> in <module>()
----> 1 tmp.foo_test()

/Users/pi/code/ipython/bar.pyc in foo_bar()
      1 
      2 def foo_bar():
----> 3     1/0

ZeroDivisionError: integer division or modulo by zero

In [5]: debug
> /Users/pi/code/ipython/bar.py(3)foo_bar()
      1 
      2 def foo_bar():
----> 3     1/0

ipdb> w
  <ipython-input-4-f50710bfc43f>(1)<module>()
----> 1 tmp.foo_test()



> /Users/pi/code/ipython/bar.py(3)foo_bar()
      1 
      2 def foo_bar():
----> 3     1/0

ipdb> 

[ivanov]

more context: this proof-of-concept traceback filtering based on filenames