[CopyResourcesScript] Do not discard `.xcassets` from the main project if there are any pods containing `.xcassets`.

[CopyResourcesScript] Do not discard `.xcassets` from the main project if there are any pods containing `.xcassets`.

Closes https://github.com/CocoaPods/CocoaPods/issues/3301.

[CoC] Adds a code of conduct, thanks for the inspiration @indirect

[PrefixHeader] De-duplicate the contents on the prefix_header file when there are multiple subspecs with the same prefix_header

Closes https://github.com/CocoaPods/CocoaPods/issues/3283.

[CHANGELOG] Used unicode for the emojis (as GitHub emoji codes does not seem to be rendered online) #2892

Fix #3247 by adding quote to $XCASSET_FILES

[Generator] use absolute xcasset file path in copy resource script

Wrong `xcassets` path in generated `Pods-resources.sh` file. This bug
can be reproduced by adding [1PasswordExtension
spec](https://github.com/CocoaPods/Specs/blob/master/Specs/1PasswordExtension/1.1.2/1PasswordExtension.podspec.json)
to demo app.

Include Swift-specific build settings on target creation

Only copy the required xcasset files into the user bundle

[Validator] Allows Swift pods to have a deployment target under iOS 8.0 ...

[XCConfigHelper] Adds $(inherited) to generated OTHER_SWIFT_FLAGS