Added new toolbar to masking tool.
Added special icons and actions for drawing a mask over pixels.
Changes for masking improvements.
Made masking either direct or region draw.
Added nullification of cursor.
Merge branch 'master' of git@github.com:DawnScience/dawn-ui.git

Conflicts:
	org.dawb.workbench.plotting/src/org/dawb/workbench/plotting/system/PlottingSystemImpl.java
	org.dawb.workbench.plotting/src/org/dawb/workbench/plotting/tools/MaskingTool.java
Added sqaure pen implementation.
Merge branch 'master' of git@github.com:DawnScience/dawn-ui.git