code interface cleanup

[guruofgentoo]

While working through documentation, I'm tracking things that seem inconsistent/wrong/needs-refactored. We'll need to triage these into near/long term updates. A few of these may be represented in other issues.

Grid:

• identifier/ident
  • Why not have a single identifier attribute and just set it at instance time?
• features inconsistently named
  • feature flags
    • sorter_on, pager_on, session_on, etc.
    • enable_search, hide_controls_box, subtotals
• renderer attributes are set directly on the grid. Seems like they should be scoped to a renderers area.
• build method
  • not a great name, as it doesn't really build anything. This method seems to be a shortcut to running a before-query hook and producing attribute errors outside of a Jinja context, where they'd be hidden.
  • maybe init_request?
  • also not sure on the intent of the before-query hook. Perhaps it is to have a spot for modifying filters before the query is constructed. Doesn't appear to be used in any of our projects.
• _apply_filtering and _apply_paging should use the grid's set methods
  • otherwise, if ops are done to retrieve records prior to applying args, cached values will persist
  • much of the logic in paging could be moved to set_paging
• column init should set a key if it will be None
• add a set_column_order method that takes a list of keys and sets up the grid with the given column order

Column:

• Columns need a way to be added at instance time, like with an add_column method
  • helpful to set up the grid at run time, since in some cases app context is required
  • current solution is grid "factory" methods that pass the grid class back, but that seems overkill for the problem
• NumericColumn has accounting format overrides that seem unintuitive
  • should have an AccountingColumn that encapsulates these

Filter:

• OptionsEnumFilter requires enum_type to be passed as an arg. Should be able to set it as a class attribute on a subclass instead.
• set should make value1 optional as well. Many operators do not have inputs.