Send OSC 4 codes to set baseline 16 colors to DOS/CGA palette

Since many modern terminals support OSC 4 codes to set the baseline 16 colors, it would be beneficial for connections to set the colors to match the expected ANSI palette on connection, especially if UTF is detected/supported.

This will improve the experience for users that are simply using their OS terminals to connect to BBSes over SSH/Telnet directly.