Set number of course sections to a reasonable value when course content is imported

Steps to reproduce:

• Create a course A
• Set the number of course sections of course A to > 1
• Fill the course sections of course A with some activities
• Create a course B
• Set the number of course sections of course B to 1
• Fill the course sections of course B with some activities
• Go to course A
• Open the Course administration -> Import menu item
• Import content of more than one section from course B into course A

Actual result:

• In course A, section number 1 is visible and shows the imported content
• In course A, section number 2 and so on are not visible and are only shown as orphaned activities when editing mode is on

Expected result:

• In course A, the number of sections is set to a reasonable value and all sections which were imported from course B are visible to students without having to change anything to change orphaned activity sections to real sections.