Introducing flat options (#984)

* Initial commit

* Remove HybridExample (#985)

* Remove HybridExample

* Remove last mention of HelloHybrid

* Remove console log

* Fix flow and example

* Fix routers api docs

* Keep options in single place

* chore

* Fix styling

* Organise miscs

* Better flow type for screen options

* Flow test website and add more types to options

* navigationOptions instead of prevOptions makes more sense

* Fixes

* Fix up docs

* Fix

* Update route decl

* Provide error when removed API is used

* Remove lock

* Add validators

* Make StacksOverTabs config valid again

* Do not return

* Fix redbox

.github/PULL_REQUEST_TEMPLATE.md

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+Please provide enough information so that others can review your pull request:
+
+Explain the **motivation** for making this change. What existing problem does the pull request solve?
+
+Prefer **small pull requests**. These are much easier to review and more likely to get merged. Make sure the PR does only one thing, otherwise split it.
+
+**Test plan (required)**
+
+Demonstrate the code is solid. Example: The exact commands you ran and their output, screenshots / videos if the pull request changes UI.
+
+Make sure you test on both platforms if your change affects both platforms.
+
+The code must pass tests and shouldn't add more Flow errors.
+
+**Code formatting**
+
+Look around. Match the style of the rest of the codebase.