Add an Example and modifications to the interactive executor to enable Llava Models.

Just a preview / demo

- UserSettings, simplifying the validation/re-ask loop down to one call
 - Program, adding colour to figlet title
 - Batched examples, showing default prompt
 - ExampleRunner, resetting state after running an example

* LLama.Examples: RepoUtils.cs → ConsoleLogger.cs

* LLama.Examples: Examples/Runner.cs → ExampleRunner.cs

* LLama.Examples: delete unused console logger

* LLama.Examples: improve splash screen appearance

the llama_empty_call() no longer shows configuration information on startup, but it will display it automatically the first time a model is engaged

* LLama.Examples: Runner → ExampleRunner

* LLama.Examples: improve model path prompt

The last used model is stored in a config file and is re-used when a blank path is provided

* LLama.Examples: NativeApi.llama_empty_call() at startup

* LLama.Examples: reduce console noise when saving model path