Category filter removes when click next

[jordan-featherstone]

Hey,

I was just wondering if there is a quick fix to keep the category filter in the url when the 'Next' or 'Previous' button is pressed in Month view

[Tyrdall]

Hi!

As far as I can see it's only a small change here

django-calendarium/calendarium/views.py

Line 70 in cabe69e

if request.POST.get('next'):

Simply copy the GET parameters.

Feel free to post a pull request!