External editor

Hello,

First of all I'd like to thank all the developers of pgadmin for your
remarkable product, it really helps.
After some experience of working on relatively large project, I have
found internal function editor not very suitable for creation and
editing of large functions because of it's size, tabulation absence and
font troubles. I didn't find in ToDo list any remarks about editor, so
as an option, I think it would be fine to have support for external
editor.
It's not a big deal but will work for function creation and editing.

Thank you,

Alexander Nikitin