MDL-36795 - lib / administration: maxsections now limits the default setting for...

MDL-36795 - lib / administration: maxsections now limits the default setting for numsections.

In the default course settings, setting the maximum number topics / weeks  to 0 would not
change the default number of sections on the same page as any other number would.
A more appropriate check has been put in place.

This also incorporates a fix for MDL-28584. The course edit screen now also checks to see
if maxsections is set or numeric. If it is not set or numeric then it defaults to 52.