Make the startup flag "-nodisplay" optional

[kamesy]

For showing figures matlab must be started without the "-nodisplay" flag.

[tqml]

Hey @kamesy! thanks for the PR! Seems like a good addition.

For me, it would be fine to change the default here, as it would be easier for new user. What do you think @musm?

We could also document a way by using a custom MSession on changing the behavior.

For example:

new_session_flags = ""
new_session = session = MATLAB.MSession(MATLAB.default_output_buffer_size; flags=new_session_flags)
MATLAB.close_default_msession()
MATLAB.default_msession_ref[] = new_session