place location provided by peg 0.9 onto the AST

[jimmyhchan]

Since we are now using peg 0.9, it'll be useful to have the end line, end column and offset. Offset is useful for parser authors who want to splice on the file buffer (get the template text for a helper for instance).

Up for discussion:

• I'm dumping all of location into the location property of the peg node for max back compat. It's meta data so it seems cleaner.
• I'm removing the extra line/column from the ast so it's a breaking change

[sethkinast]

I am so happy to get rid of the stuff off the AST

[sethkinast]

You found the other line/col thing I was thinking of. I think this is great! I'll pull it in locally and spot check a bit before merging if someone else can review too.