GUI for generating the data source string

[shankar-roy]

We are trying to leverage ELK for our log monitoring. As part of that there is a need to be able to compare tends and patterns over different time regions. Users are not comfortable generating the data source string by hand. Request is for a gui so that it can be generated graphically.

[rashidkpc]

I'm open to it, the whole thing gets built into an AST, so in theory you could create an alternate end point that takes the AST as an input instead of the string, making the interface easier to build.

Of course, it would be more difficult to maintain since the AST is more likely to change than the expressions.

[ddavidebor]

@tania90 did you intended composing the Elasticsearch query .es(query) ? or more generally writing all the chains of function to display them on the plot?

I'd love to hear your case to see if what we're developing is #174 is a useful enhancement.