GeneratorNG: Added initial implementation for methods generation.

Enabled only for messages methods for now.
Small refactor. Prepairing to code generation.
CTelegramStream: Added TLInputEncryptedChat write operator.
GeneratorNG: Code extracted to GeneratorNG class.
GeneratorNG: Implemented write stream operators generation.
CTelegramStream: Regenerated.
CTelegramConnection: Added generated "messages" group methods.
Added initial support for sent messages delivery reports.
testApp: Reimplemented messaging.