add pudb + configuration

[arne-cl]

• add pudb (for Python 2 and 3)
• add config file

$ cat .config/pudb/pudb.cfg 
[pudb]
breakpoints_weight = 1
current_stack_frame = top
custom_shell = 
custom_stringifier = 
custom_theme = 
display = auto
line_numbers = True
prompt_on_quit = True
seen_welcome = e033
shell = ipython
sidebar_width = 0.5
stack_weight = 1
stringifier = str
theme = classic
variables_weight = 1
wrap_variables = True