separate default apps from python

[taylorchu]

you can actually let python to parse a list of default programs.

i.e.
file extension:program1,program2,program3
doc:libreoffice,openoffice

so users dont have to touch ranger to modify the default programs.
I think the current default.py is really messy because each time a program is added, you will have to add a new handler or modify the python code.

[hut]

working on it

[taylorchu]

i think rifle.py works really well. thanks and close.