Feature request: query by character position (range)

[mattpardee]

I'd love to tell someone what something is where their cursor is. Is it possible to query by "range"? For example, I could pass tree.atPosition(48) and it would return

Node {
       type: 'CallExpression',
       start: 47,
       end: 62,
       range: [Object],
       callee: [Object],
       arguments: [Object] }

[mattpardee]

Great tool by the way, thank you for building it!