AnsiEscapeCodeHandler: Make enum private

Change-Id: Ie61567ed6af444ff01a09eeb77399c48163c04c1
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
AnsiEscapeHandler: Use a dedicated struct in favor of a qPair

Change-Id: I800d4868caf0cd58f83507ae2d0849d50f86a01f
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
AnsiEscapeHandler: Avoid some iterations over the string

Find the first escape sequence by iterating over the string once
and reuse that value during the complete initialization.

Change-Id: I6a4dd3bb4da97923410a99dbb03210ffdc6ae27f
Reviewed-by: Daniel Teske <daniel.teske@digia.com>