The tool-system it's self is primitive and may be changed.
Adding to 2.8 to develop operators and manipulators as tools.
Currently this is exposed in the toolbar, collapsed by default.
Work-flow remains unchanged if you don't change the active tool.
Placing the 3D cursor is now a Click instead of a Press event,
this allows tweak events to be mapped to tools such as border select,
keeping click for 3D cursor placement when selection tools are set.
