If numpy not installed then OpenREM fails to run.

[David Platten]

views.py tries to import numpy. If numpy is not present then OpenREM doesn't work at all.

[David Platten]

I have fixed this by putting in a check in views.py that numpy can be imported. Now works fine. If numpy isn't available then OpenREM still works, but the plots on the web pages are blank.

I will add some code to the web pages to only make the plots visible if there is data present in the arrays.

[David Platten]

I have added some code to dxfilterted.html to check for plot data. If none is available then the plots are not shown. If there is data, then the plots are shown.

[David Platten]

This resolves issue #136 of some users possibly not having numpy installed.