ChatSecureCore.framework migration

[chrisballinger]

Work is ongoing in the framework branch. ChatSecureCore.framework should be split into sub-frameworks each concerned with a specific domain (e.g. network, database, encryption, UI, assets).

• Move all source code from ChatSecure app target to ChatSecureCore.framework target
• OTRClassCustomization Protocol to provide alternative subclasses for commonly overridden views. Implemented by OTRAppDelegate and whitelabel app delegate subclasses.
• Identify old/legacy code that can be removed, and remove it.
• During sub-framework migration, identify and minimize the public API exported by each framework.
• OTRAssets.framework - separate framework for app resources to override brand-specific images and other resources
• OTRUserInterface.framework - non platform specific UI code
• OTRUIKit.framework - all iOS UIKit code goes here
• OTRAppKit.framework - all Mac AppKit code
• OTRNetwork.framework - XMPP, nearby/airshare
• OTRDatabase.framework - data models, YapDatabase, etc
• OTRCrypto.framework - OTR, Tor, Axolotl

Right now there are some missing image resources caused by the framework migration. Fixing this will require a special approach to ensure the resources are easily overridable from a different whitelabeled app target. Simply bundling the resources within ChatSecureCore.framework will not work because you won't be able to override them.