Update with changes in Xcode 6.1 Beta 3 / Yosemite GM seed.
Merge pull request #64 from nschum/xcode61gm

Update with changes in Xcode 6.1 GM.
fix link
Changed in Xcode 6.1 GM Seed 2
"Yosemite GM" -> "GM Seed 1"
Optionals in imported Objective-C frameworks "as of"
Additional info and links for 6.1 GM seed 1
GM Seed naming quote
Update README.md
Date of the next release
Optional methods in pure-Swift protocols
Optionals in imported Objective-C frameworks (6.1 update)
Remove "Swift 1.1 scope" — 1.1 has shipped
Update 6.1 GM Seed 2 + 6.1 final
Fix link + RN links
extra quote for flow-sensitive unwrapping
Add section on ABI stability

- http://en.wikipedia.org/wiki/Application_binary_interface
Add section about runtime dynamic libraries
Merge pull request #67 from beltex/abi

Add section on ABI stability
Merge pull request #68 from beltex/runtime

Add section about runtime dynamic libraries