Pull request - from_date

Hi all,

I'm Luke and I've been using getmail for quite a few years already and 
I've always been very happy of the product. Thanks to developers for the 
effort!

In the last days I was looking for a way to discard the retrieval of 
email messages up to a certain date. This is somehow similar to the 
option 'max_message_size' but for dates.

I then realized there is no such feature (yet) available so I decided to 
download the code and dig into it. Long story short I extended the code 
to add this extra option to avoid the download of emails (I called it 
'from_date')

So, I would like to hear from you if you might be interested to merge 
this feature into the code base. Just let me know and I will send you 
the changes (at the time of writing I'm working with version 5.14)


Regards,
Luke