Consolidates all the pql.Call implementations into a single
pql.Call struct. This is needed to support user-defined schemas
on frames.
This also has the added benefit that a lot of redundant parsing
code has been consolidated.
This commit adds the ability to set string, integer, and boolean
values on bitmaps and profiles within Pilosa. Bitmap attributes
are automatically returned when making a `Bitmap()` call. Profile
attributes must be requested by setting `profile=true` in the
URL.
The function names have also been renamed to initial caps so that
the PQL query language can support math operations in the future.
This commit refactors the pilosa codebase. It makes several major
changes:
* Removes bitmap handles
* Removes dispatch/hold/transport
* Removes etcd dependency
* Adds consistent hash ring for slice placement
* Refactors parser/lexer
* Adds strong typing to PQL AST
* Flattens package hierarchy
