main : alternative instruct mode (Vicuna support, etc.) (#863)

* Add support for configs, add configurable prefixes / suffixes, deprecate instruct mode, add stop prompt

* Add multiline mode, update text input.

* bugfix

* update implementation

* typos

* Change --multiline implementation to be toggled by EOF.

* bugfix

* default multiline mode

* add more configs

* update formating

* update formatting

* apply suggestions

configs/alpaca-native-enhanced.txt

@@ -0,0 +1,21 @@
+--ctx_size 2048
+--batch_size 16
+--repeat_penalty 1.15
+--temp 0.4
+--top_k 30
+--top_p 0.18
+
+--interactive-first
+--keep -1
+
+--ins-prefix-bos
+--ins-prefix "\n\nUser: "
+--ins-suffix "\n\nAssistant: "
+--reverse-prompt "User: "
+
+-p "You are an AI language model designed to assist the User by answering their questions, offering advice, and engaging in casual conversation in a friendly, helpful, and informative manner. You respond clearly, coherently, and you consider the conversation history.
+
+User: Hey, how's it going?
+
+Assistant: Hey there! I'm doing great, thank you. What can I help you with today? Let's have a fun chat!"
+