More text changes and HTML cleanup.
Changed D3 version to 3.4.11 in order to use d3.locale for Dutch number formatting. This broke some transitions, but these were fixed by initializing the rect values in the enter phase (also starting from the color white instead of default black). Charts now work with negative values as well! Also added a little hack to draw an x-axis line along the whole width of the chart. Added .nice() to the bar chart y-axis. Some code cleanup.