Add support for a non-terminal console mode

If a process is running under control of winpty, the output of the process is decorated with ESC sequences to control a terminal to print the process output nicely. In some environments however, the client showing the output to the user is not a full terminal emulation, the Eclipse CDT debug console view in example, and the ESC sequences are printed as output additional to the real process output. This commit is adding an API function to switch into a mode where winpty is not decorating the process output with ESC sequences. The console mode is designated to pass on the process output to the client as is.