Straightforward improvements to InlineEdit implementation

Our InlineEdit component is one of our very oldest components, and contains a number of "implementation features" that would not appear in a new component which would be written today. Whilst we have a strong commitment to API compatibility, there are a number of low-cost improvements we could make today without compromising compatibility and also heading off possible bugs as well as improving consistency and reusability.

i) A group of issues referred to under FLUID-4725 -
a) use of a mergePolicy rather than manual code for options defaulting
b) migrating the tooltipText option up into strings as with defaultViewText
c) FLUID-4732 - inserting component's options into the proper namespace
d) amalgamating DOM element arguments for the highlight and edit mode binders - which implies
ii) fixing up implementation of the range of event binding functions so that they are all consistent in accepting a multi-element jQuery as their first argument (where they currently accept any element-like thing) rather than their rather ad-hoc current use of fluid.wrap and fluid.unwrap
iii) breaking out all of these utility functions into properly namespaced functions under fluid.inlineEdit rather than using our old-fashioned approach which still valued private anonymous implementation details.
iv) improvement of argument names - the name "displayModeRenderer" should be replaced with something more descriptive (at least where this term doesn't appear in a public API), as well as the misuse of the term "selector" on line 718