* Fix some of the problems with alignment. Alignment issues arise from few issues. Main concern seems to be rounding errors when setting dimensions on Dimension class which only operates on integer accuracy - floats would be nicer. Rendering the graph in larger chunks (step variable) and cutting them to pieces somewhat eases this. Still, when rendering levels that are deep there may occur rounding errors which lead to (slightly) misaligned nodes when zooming from one level to another. Also tiles on the border may get cut because eg. tileWidth * tilesOnXAxis does not fully cover the complete dimensions of the model (or alternatively covers too much, depending on rounding). 

Few possible ideas to improve rendering logic:

1. Using rendering logic that renders eg. one x-row at a time or y-column at a time (and then cut to pieces) might be memory friendly and not produce such alignment issues.

2. Pre-scaling coordinates to be broader scale on the graph might also be an alternative. This way rounding would not become a problem - at least not so much so.

* Add verbosity on progress bar, currently rendered tile

* Fix export not working initially if the preview model wasn't refreshed