Use normal cursor for disabled buttons

Disabled buttons now use the "auto" mouse cursor style
to give further visual information that the button can not be used.
Merge branch 'feature/button-cursor-style' of https://github.com/ceari/echo3
Merge pull request #38 from chrismay2/feature/eclipse-project

Accepting updates to Eclipse-Project by @chrismay2
Merge branch 'feature/eclipse-project'