Support for white-space normal in content of range items

[jasonex7]

The css property white-space is set nowrap in .vis-item .vis-item-content element:

vis-timeline/lib/timeline/component/css/item.css

Lines 92 to 93 in 57e091f

	.vis-item .vis-item-content {
	white-space: nowrap;

If the user wants to set white-space to normal for the content adjust dynamically, then the height of group should be calculated accordingly, but this doesn't occurs:

Code Example: https://jsfiddle.net/qu9t7dr2/1/
Tested with timeline v5.1 and last version from repo in Chrome V77