RELEASE: Merge branch 'cf7-3p9'
more forms plugin sharing; form plugin base class (for ninjaforms)

* moved email, failure format helpers to base plugin
* started base class for form plugins
minor commenting
removing ninja comments
better fplugin inclusion by hook; fplugin id in form title
werking!
fix: merging post with submission retain numeric indices
fix: php 5.4 pass by reference issues
v1.6 ninja forms integrated; other extensions using fplugin_base

* example of how to hook additional form plugins in 'includes.php'
* merged ninjaforms extension from separate plugin
* refactored cf7 and gf extensions like ninjaforms
* optional SET_BAD_MESSAGE hook `_show_warning` (prefixed by extension)
readme 1 change
upgrade path for service settings (v1.6.1); get_settings & get_services

* now ability to upgrade plugin and update settings too!
* helpers for getting settings and getting services, stashing, to make future changes easier
ui uses save_settings + save_services; fix upgrade formids
just in case...upgrading preserves non-numeric formids
fix: fplugin, etc get recipient method names

! weird - does case not matter to methods?
actually fixing the GET_RECIPIENT issue (so there was an abstract meth!)
fix: cf7 SET_BAD_MESSAGE add'l settings; fix: empty servicefailure

* contact form 7 additional_settings (js) can't have newlines, but was
being provided with the formated 'failure message' rather than the 'safe
message' as previously; included that, updated other hooks
* fixed flipped ternary for empty $confirmation/safe_message use
applying similar multi-confirmation 'cheat' to cf7 as gf
fix: fpluginbase "overwriting" submission from unused plugin hooks
fix: gravity forms confirmation message
readmes updated