v0.7.7

Improvements:

• MXFileStore: Do not store the access token. There is no reason for that.
• Improve disk usage: Do not use NSURLCache. The SDK does not need this cache. This may save hundreds of MB.
• Add E2E keys export & import. This is managed by the new MXMegolmExportEncryption class.

Bug fixes:

• Fix a few examples in the README file, thanks to @aapierce0 (PR #230).
• Duplicated msg when going into room details (https://github.com/vector-im/riot-ios#970).
• App crashes a few seconds after a successful login (https://github.com/vector-im/riot-ios#965).
• Got stuck syncing forever (https://github.com/vector-im/riot-ios#1008).
• Local echoes for typed messages stay (far) longer in grey (https://github.com/vector-im/riot-ios#1007).
• MXRealmCryptoStore: Prevent storeSession & storeInboundGroupSession from storing duplicates (#227).
• MXRealmCryptoStore: Force migration of the db to remove duplicate olm and megolm sessions (#227).