Issues #1, #2 and #4 fixed.

[maciejkorzepa]

Problems removed:
Issue #1: Every time board was resized, the old text element wasn't removed and a new one was appended in location feature.
Issue #2: Display which is an object was iterated as an array which didn't work and consequently old elements weren't removed from the track in reset function in composite feature.
Issue #4: In axis feature, rect element was removed in reset function, so the background kept disappearing when the board was resized.

I also looked into Issue #3 and I located the problem, but I didn't know how (and whether) you would like to solve that. Actually, now the problem is a bit different as fixing issue #2 changed it a bit - now only one line/area stays and the rest is removed on resize. In create function in line and area features, all the path elements within a track are removed, so only the last one to be rendered will stay on the screen. But as all the elements from different features are children of track element and don't have any classes/ids, it's not really possible to distinguish between different lines/areas within one track. A solution could be to put every feature from a composite feature into a separate (and maybe with class as the feature key given in the retriever) which would be placed as children of track element.