Add stability message for Atom.io API

This indicates that the Atom.io API is not frozen - this is describing the state
of things, not announcing a new policy.
Only autoscroll in model when adding selection in React editors

Fixes atom/find-and-replace#245
Fix autoscroll specs for addSelectionForBufferRange
Upgrade to language-coffee-script@0.25
Default cursor on scrollbars.

Fixes #2876
Upgrade to whitespace@0.24
:memo: Add Windows installation instructions
Upgrade to find-and-replace@0.126
Index line decorations by ids

And don’t use _.deepContains
Merge pull request #2888 from atom/bo-speedup-decoration-render

Index line-wise decorations by ids
Change some heading levels and add rename doc
Add error type to package version doc
Update decoration API docs
Add return statement docs
Fix typo
Merge pull request #2904 from maschs/ms-fixTypo

Fix typo
Upgrade to apm 0.72
Map ctrl-f4 to core:close command on Windows

Closes #2903
Upgrade to apm 0.73
== -> is