Basic instructions

Hello. Enter some Dhall code in the text area at the bottom of the page (wait for the checkmark to say it has parsed correctly; sorry, no multi-let yet!). Click on the pencil near the bottom to paste the parsed code onto the selected node (the top node is selected by default; click the bulls-eye next to a node to select it). Click on the "cpu" icon to see the normalized AST, the "type" icon to see its type, the "plus" icon to add a new view of the (same) expression, etc. Better type errors on the way soon!!!!