Add entryPrism function
Add undoPush function - undo/redo with explicit state push
Initial commit of some demos from "7guis", much of the code written at budhac
Merge branch '7gui-demos' of https://github.com/mgsloan/lgtk into mgsloan-7gui-demos

Conflicts:
	lgtkdemo/LGtk/Demos/Main.hs
	src/LGtk.hs
Merge branch 'mgsloan-7gui-demos'