Supprorting material with administrative issues slides

Supporting slides for the git demo lecture

Presentations including the footer should set the LECTURE_TOPIC
LECTURE_NO attributes so that the proper information is displayed
in the footer area of the presentation.

Example:
:LECTURE_TOPIC: Git demo
:LECTURE_NO: 4th lecture

Merge branch 'lectures2020' of https://gitlab.stud.idi.ntnu.no/it1901/course-material into lectures2020

slides
Header and footer includes have been added

Merge branch 'lectures2020' of https://gitlab.stud.idi.ntnu.no/it1901/course-material into lectures2020

Merge branch 'issue-11-allow-user-to-enter-and-update-metadata-about-the-latlong-points' into 'master'

Issue 11 allow user to enter and update metadata about the latlong points

Closes #10 and #11

See merge request !6

changed isCustomProperty to static
minor changes for formatting

features  MR !6

* fixed removal of items by using the iterator method
* removed couple of unnecessary if (iterator.hasnext ...) that were
surrounding a while (iterator.hasnext ...)

related to the MR !6

removed commented code block

* Used an ordinary for loop instead of the foreach as both values and
names are in the same list and I need to loop through names only
* Removed the intermediary result boolean variable and returned directly
without breaking the loop
* Added the has otherProperties(String ...) method

this should fix issue #11

Merge branch 'issue-10-display-latlong-metadata-in-the-fx-ui' into issue-11-allow-user-to-enter-and-update-metadata-about-the-latlong-points

this should fix issue 10

entries
loading the new image for the delete icon (x)

added a white x png which fits better the ui