allow characters / and = in metric names

this is still not very good way to parse though,
this will need an overhaul
various parsing and code generation fixes + alias function

* replace token scanner with simple string split, that's all we need
  this allows better logic that is more robust (we get full unsplitted
  arguments to functions etc)
* support functions that have variable types of arguments,
sometimes a string like "foo.bar" is a metric neading ReadMetric(),
sometimes it's just a string and just needs quotes around it.
Things like ints and floats don't need anything special
This also means keeping track of previous function and positions while
we traverse a call tree
* support alias function which updates the name of a target series
support listing metrics from stores & /metrics/index.json
more flexible from/to format
don't require ending slash for /render
gofmt
fix quoting of strings
timespec parsing fixes and updates
metrics can have arbitrary dots now, as cmd parsing is more robust
fix json format problem
implement CORS so you can use it from external dashboards
bugfix: don't 'fill' missing datapoints by going back in time, use correct ts
add ability to use "s" or "" for "seconds"