Treemapper general usability improvments

[gion86]

I'm using the treemapper widget in one of my projects, and I've made some small usability improvements. Most of them are about dynamic configuration of the widget behaviour:

• ISemanticTreeMapperSupport.java: method to enable or disable the warning in case of fail in item resolution
• TreeMapperUIConfigProvider.java: support for "drag and drop" enable and custom weights for the tree's control layout
• TreeMapper.java: method to update the canvas draw, offset for tree mapping drawing based on the tree header height

I will make a PR for this.

Thankyou! Gionata

[lcaron]

Hi Gionata

Welcome on board !

I'll have a look at this PR.