Primary API for HoneySQL 2.x.

This includes the `format` function -- the primary entry point -- as well
as several public formatters that are intended to help users extend the
supported syntax.

In addition, functions to extend HoneySQL are also provided here:
* `clause-order` -- returns the current clause priority ordering;
      intended as aid when registering new clauses.
* `format-dsl` -- intended to format SQL statements; returns a vector
      containing a SQL string followed by parameter values.
* `format-entity` -- intended to format SQL entities; returns a string
      representing the SQL entity.
* `format-expr` -- intended to format SQL expressions; returns a vector
      containing a SQL string followed by parameter values.
* `format-expr-list` -- intended to format a list of SQL expressions;
      returns a pair comprising: a sequence of SQL expressions (to be
      join with a delimiter) and a sequence of parameter values.
* `register-clause!` -- register a new statement/clause formatter.
* `register-fn!` -- register a new function call (or special syntax)
      formatter.
* `register-op!` -- register a new operator formatter.
* `set-dialect!` -- set the default dialect to be used for formatting,
      and optionally set a global `:quoted` option.
* `sql-kw` -- turns a Clojure keyword (or symbol) into SQL code (makes
      it uppercase and replaces - with space). 

  (-> (select :a :b :c)
      (from :table)
      (where [:= :id 42])
      (sql/format))

  (-> {}
      (select :a :b :c)
      (from :table)
      (where [:= :id 42])
      (sql/format))

bulk-collect-into [varname] [varname n]

bulk-collect-into [dsl varname] [dsl varname n]

bulk-collect-info [& args]

Helper functions for the built-in clauses in honey.sql.

  All helper functions are inherently variadic. Typical
  usage is threaded, like this:

```
  (-> (select :a :b :c)
      (from :table)
      (where [:= :id 42])
      (sql/format))
```

  Therefore all helpers can take an existing DSL expression
  as their first argument or, if the first argument is not
  a hash map, an empty DSL is assumed -- an empty hash map.
  The above is therefore equivalent to:

```
  (-> {}
      (select :a :b :c)
      (from :table)
      (where [:= :id 42])
      (sql/format))
```

  Some of the helper functions here have `:arglists` metadata
  in an attempt to provide better hints for auto-complete in
  editors but those `:arglists` _always omit the DSL argument_
  to avoid duplicating the various argument lists. When you
  see an auto-complete suggestion like:

    bulk-collect-into [varname] [varname n]

  bear in mind that a DSL hash map can always be threaded in
  so the following (pseudo) arities are also available:

    bulk-collect-into [dsl varname] [dsl varname n]

  The actual arguments are:

    bulk-collect-info [& args]

  (as they are for all helper functions).